Every Day Counts
Centred Square Prime Days
 
Age: 13,730 days
Date of birth
Your 30th Centred Square Prime Day is on
Wednesday
when you will be
14,281 days old

A centred square prime is a centred square number that is prime.

Unlike regular square numbers, which are never prime, quite a few of the centred square numbers are prime.

Centred square numbers are of the form n2 + (n - 1)2

In elementary number theory, a centred square number is a centred figurate number that gives the number of dots in a square with a dot in the centre and all other dots surrounding the centre dot in successive square layers. That is, each centred square number equals the number of dots within a given city block distance of the centre dot on a regular square lattice. While centred square numbers, like figurate numbers in general, have few if any direct practical applications, they are sometimes studied in recreational mathematics for their elegant geometric and arithmetic properties.

The figures for the first four centred square numbers are shown below:

Remind me, please


Next Prime Events
Day Age
Event
Days Ahead
Year Age
12 Oct 2018
13,751
21
37
31 Dec 2018
13,831
101
37
01 Jan 2020
14,197
467
38
25 Mar 2020
14,281
551
39
18 Nov 2020
14,519
789
39
16 Oct 2021
14,851
1,121
40
14 Apr 2025
16,127
2,397
44
20 Sep 2026
16,651
2,921
45
31 Mar 2027
16,843
3,113
46
13 Jan 2029
17,497
3,767
47
28 Nov 2030
18,181
4,451
49
22 Mar 2034
19,391
5,661
53
19 Sep 2035
19,937
6,207
54
04 Aug 2059
28,657
14,927
78
31 Mar 2114
48,619
34,889
133
25 Jul 2160
65,537
51,807
179
08 Sep 2255
100,279
86,549
274
29 Dec 2339
131,071
117,341
358
Ordinal
Day Age
Date
Age
1st
5
22 Feb 1981
0
2nd
13
02 Mar 1981
0
3rd
41
30 Mar 1981
0
4th
61
19 Apr 1981
0
5th
113
10 Jun 1981
0
6th
181
17 Aug 1981
0
7th
313
27 Dec 1981
0
8th
421
14 Apr 1982
1
9th
613
23 Oct 1982
1
10th
761
20 Mar 1983
2
11th
1,013
27 Nov 1983
2
12th
1,201
02 Jun 1984
3
13th
1,301
10 Sep 1984
3
14th
1,741
24 Nov 1985
4
15th
1,861
24 Mar 1986
5
16th
2,113
01 Dec 1986
5
17th
2,381
26 Aug 1987
6
18th
2,521
13 Jan 1988
6
19th
3,121
04 Sep 1989
8
20th
3,613
09 Jan 1991
9
21st
4,513
27 Jun 1993
12
22nd
5,101
05 Feb 1995
13
23rd
7,321
05 Mar 2001
20
24th
8,581
16 Aug 2004
23
25th
9,661
01 Aug 2007
26
26th
9,941
07 May 2008
27
27th
10,513
30 Nov 2009
28
28th
12,641
28 Sep 2015
34
29th
13,613
27 May 2018
37
30th
14,281
25 Mar 2020
39
1
31st
14,621
28 Feb 2021
40
32nd
15,313
21 Jan 2023
41
33rd
16,381
24 Dec 2025
44
34th
19,013
09 Mar 2033
52
35th
19,801
06 May 2035
54
36th
20,201
09 Jun 2036
55
37th
21,013
30 Aug 2038
57
38th
21,841
05 Dec 2040
59
39th
23,981
15 Oct 2046
65
40th
24,421
29 Dec 2047
66
41st
26,681
07 Mar 2054
73