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

Author

Vladimir Joseph Stephan Orlovsky, Apr 27 2010

Keywords

• nonn

Comments

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

Examples

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

Links

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

Crossrefs

Cf. A053186.

Programs

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