A056904 Floor[p/24] where p is a prime which is 4 more than a square.

0, 0, 1, 2, 7, 9, 12, 30, 45, 51, 57, 84, 92, 135, 176, 187, 222, 301, 315, 376, 392, 442, 551, 570, 651, 759, 782, 900, 1001, 1107, 1162, 1305, 1395, 1552, 1717, 1785, 1926, 1962, 2262, 2301, 2460, 2501, 2667, 2709, 2926, 2970, 3151, 3197, 3432, 3577, 3825

Offset: 0

Author

Henry Bottomley, Jul 06 2000

Keywords

• nonn

Examples

			a(2)=1 since 29 is a prime which is four more than a square and floor[29/24]=1
		

Crossrefs

a(n) is contained in A001840. A005473(n)=24*a(n)+m, where m=13 if a(n) is three times a triangular number (and n>0) i.e. in A045943 and m=5 if A056904(n) is not three times a triangular number (or n=0) i.e. in A001318.

Programs

Mathematica

Join[{0},Floor[#/24]&/@Select[Prime[Range[10000]],#-Floor[Sqrt[#]]^2 == 4&]] (* Harvey P. Dale, Oct 25 2011 *)
With[{nn=400},Floor[#/24]&/@Select[Range[nn]^2+4,PrimeQ]] (* Harvey P. Dale, Dec 02 2021 *)

Formula

a(n) =floor[A005473(n)/24]