12 = 2^2 * 3

12 = 3 + 4 + 5 which makes it the third term of the sequence A027480.

12 = 5 + 7, i.e. the sum of two consecutive primes.

12 is a member of two primitive, Pythagorean triples (5, 12, 13) and (12, 35, 37).

Starting at 0, write the numbers down in a clockwise spiral. 12 is the third term in one of the diagonals.

42 43 44 45 46 47 48

41 20 21 22 23 24 25

40 19 6 7 8 9 26

39 18 5

*0*1 10 27

38 17 4 3

*2*11 28

37 16 15 14 13

*12*29

36 35 34 33 32 31

*30*

This diagonal gives the sequence 0, 2, 12, 30, 56, 90 132 ... which has the formula 2n(2n - 1).

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