|
%I #6 Nov 09 2022 13:27:16
%S 2,3,5,7,11,13,19,47,101,157,331,457,569,1069,1237,1471,1667,2161,
%T 2467,2719,3061,3719,4027,4441,5227,5591,6469,6991,7411,9011,11287,
%U 14407,15797,16607,18097,21269,21997,24697,29221,30319,32321,35311,38711
%N Primes of the form p=floor(T/4), T are Triangular numbers.
%H Harvey P. Dale, <a href="/A171574/b171574.txt">Table of n, a(n) for n = 1..1000</a>
%e floor(10/4)=2, floor(15/4)=3, floor(21/4)=5,..
%t f[n_]:=n*(n+1)/2;lst={};Do[If[PrimeQ[p=Floor[f[n]/4]],AppendTo[lst,p]],{n,7!}];lst
%t Select[Floor[Accumulate[Range[600]]/4],PrimeQ] (* _Harvey P. Dale_, Nov 09 2022 *)
%Y Cf. A000217
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Dec 12 2009
|
