A176864 Numbers k such that A053186(k) is prime.

3, 6, 7, 11, 12, 14, 18, 19, 21, 23, 27, 28, 30, 32, 38, 39, 41, 43, 47, 51, 52, 54, 56, 60, 62, 66, 67, 69, 71, 75, 77, 83, 84, 86, 88, 92, 94, 98, 102, 103, 105, 107, 111, 113, 117, 119, 123, 124, 126, 128, 132, 134, 138, 140, 146, 147, 149, 151, 155, 157, 161, 163

Offset

1,1

Comments

Numbers of the form p + j^2 where p is prime and p <= 2*j. - Robert Israel, Dec 14 2018

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

3-1^2=2, 6-2^2=2, 7-2^2=3, 11-3^2=2, ...

Maple

N:= 30: # to get all terms < (N+1)^2
Primes:= select(isprime, [2, seq(i, i=3..2*N, 2)]):
seq(op(map(`+`, select(`<=`, Primes, 2*j), j^2)), j=1..N); # Robert Israel, Dec 14 2018

Mathematica

lst={}; Do[p=n-Floor[Sqrt[n]]^2; If[PrimeQ[p], AppendTo[lst, n]], {n, 6!}]; lst

Crossrefs

Cf. A053186.

Sequence in context: A269177 A269178 A120511 * A347793 A306718 A022550

Adjacent sequences: A176861 A176862 A176863 * A176865 A176866 A176867

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Apr 27 2010

Status

approved