A226567 Numbers n such that 2n+1 is neither a square nor a prime.

7, 10, 13, 16, 17, 19, 22, 25, 27, 28, 31, 32, 34, 37, 38, 42, 43, 45, 46, 47, 49, 52, 55, 57, 58, 59, 61, 62, 64, 66, 67, 70, 71, 72, 73, 76, 77, 79, 80, 82, 85, 87, 88, 91, 92, 93, 94, 97, 100, 101, 102, 103, 104, 106, 107, 108, 109, 110, 115, 117, 118, 121

Offset

1,1

Comments

The natural numbers A000027 that are not in A005097 and A046092.

A226567 = Complement(A000027, A005097, A046092). - Zak Seidov, Jul 08 2013

Links

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

Example

n=10; n+1=11; 121-100=21; 21 is not a square nor a prime.

Maple

remove(n -> issqr(2*n+1) or isprime(2*n+1), [$1..1000]); # Robert Israel, Jun 16 2017

Mathematica

Select[Range[200], ! PrimeQ[2 # + 1] && ! IntegerQ[Sqrt[2 # + 1]] &] (* T. D. Noe, Jun 13 2013 *)

Crossrefs

Cf. A000027, A005097, A046092.

Sequence in context: A153040 A352963 A024888 * A184106 A112414 A329387

Adjacent sequences: A226564 A226565 A226566 * A226568 A226569 A226570

Keyword

nonn

Author

César Aguilera, Jun 13 2013

Status

approved