ARSE

Mon 04 Dec 2023

Centred Square Prime Days

Your 30th Centred Square Prime Day is on

Friday

26 September 2025

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
**n ^{2} + (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:

Next Prime Events

Day Age

Event

Days Ahead

Year Age

Ordinal

Day Age

Date

Age

1st

5

0

2nd

13

0

3rd

41

0

4th

61

0

5th

113

0

6th

181

0

7th

313

0

8th

421

1

9th

613

1

10th

761

2

11th

1,013

2

12th

1,201

3

13th

1,301

3

14th

1,741

4

15th

1,861

5

16th

2,113

5

17th

2,381

6

18th

2,521

6

19th

3,121

8

20th

3,613

9

21st

4,513

12

22nd

5,101

13

23rd

7,321

20

24th

8,581

23

25th

9,661

26

26th

9,941

27

27th

10,513

28

28th

12,641

34

29th

13,613

37

30th

14,281

39

1

31st

14,621

40

32nd

15,313

41

33rd

16,381

44

34th

19,013

52

35th

19,801

54

36th

20,201

55

37th

21,013

57

38th

21,841

59

39th

23,981

65

40th

24,421

66

41st

26,681

73