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A056904 Floor[p/24] where p is a prime which is 4 more than a square. 5

%I #9 Dec 02 2021 13:42:55

%S 0,0,1,2,7,9,12,30,45,51,57,84,92,135,176,187,222,301,315,376,392,442,

%T 551,570,651,759,782,900,1001,1107,1162,1305,1395,1552,1717,1785,1926,

%U 1962,2262,2301,2460,2501,2667,2709,2926,2970,3151,3197,3432,3577,3825

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

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

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

%t Join[{0},Floor[#/24]&/@Select[Prime[Range[10000]],#-Floor[Sqrt[#]]^2 == 4&]] (* _Harvey P. Dale_, Oct 25 2011 *)

%t With[{nn=400},Floor[#/24]&/@Select[Range[nn]^2+4,PrimeQ]] (* _Harvey P. Dale_, Dec 02 2021 *)

%Y 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.

%K nonn

%O 0,4

%A _Henry Bottomley_, Jul 06 2000

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Last modified April 20 00:00 EDT 2024. Contains 371798 sequences. (Running on oeis4.)