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A171595 Primes of the form p=floor(T/6), T are triangular numbers. 2
2, 3, 7, 11, 13, 17, 31, 67, 157, 229, 379, 487, 1291, 1621, 3217, 3727, 4051, 4621, 6007, 7129, 7879, 9157, 9661, 10531, 11071, 12577, 13567, 15877, 16987, 23629, 24979, 28081, 31981, 32917, 39847, 46687, 51679, 54877, 56101, 58171, 61561 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

Floor(15/6)=2, floor(21/6)=3, floor(45/6)=7,..

MATHEMATICA

f[n_]:=n*(n+1)/2; lst={}; Do[If[PrimeQ[p=Floor[f[n]/6]], AppendTo[lst, p]], {n, 7!}]; lst

Select[Floor[#/6]&/@Accumulate[Range[1000]], PrimeQ] (* Harvey P. Dale, Jul 23 2012 *)

CROSSREFS

Cf. A000217, A171574

Sequence in context: A278698 A023221 A127430 * A106483 A145673 A321657

Adjacent sequences:  A171592 A171593 A171594 * A171596 A171597 A171598

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Dec 12 2009

STATUS

approved

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Last modified July 11 23:53 EDT 2020. Contains 335654 sequences. (Running on oeis4.)