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A159049
Primes of the form (5+ a triangular number A000217).
2
5, 11, 41, 71, 83, 281, 383, 1181, 1601, 2351, 2633, 3491, 3833, 4283, 5783, 6221, 6791, 8783, 10301, 10883, 11633, 12251, 14033, 15581, 18341, 26111, 26801, 30881, 31883, 34721, 38231, 41333, 41621, 42491, 43961, 46061, 47591, 53633, 60383
OFFSET
1,1
LINKS
EXAMPLE
11 is in the list because it is A000217(3)+5 and a prime. 41=36+5= A000217(8)+5 is a prime. 71=66+5=A000217(11)+5 is a prime.
MATHEMATICA
s=0; lst={}; Do[s+=n; p=s+5; If[PrimeQ[p], AppendTo[lst, p]], {n, 0, 7!}]; lst
Select[Accumulate[Range[0, 500]]+5, PrimeQ] (* Harvey P. Dale, Jul 08 2017 *)
PROG
(PARI) for(n=1, 500, if(isprime(k=n*(n+1)/2 + 5), print1(k, ", "))) \\ G. C. Greubel, Jul 13 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Definition rephrased, R. J. Mathar, Apr 05 2009
STATUS
approved