A255491 Numbers k such that 90*k+1 is composite.

1, 4, 5, 8, 10, 12, 14, 15, 16, 19, 21, 22, 23, 27, 29, 30, 32, 35, 36, 38, 40, 42, 43, 44, 46, 48, 49, 50, 52, 53, 56, 57, 58, 59, 60, 61, 63, 64, 66, 67, 71, 75, 77, 78, 79, 80, 81, 82, 83, 85, 87, 88, 92, 93, 95, 99, 103, 104, 105, 106

Offset: 1

Author

N. J. A. Sloane, Mar 03 2015

Keywords

• nonn

References

• J. W. Helkenberg, Email message, Mar 02 2015.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..7000

Crossrefs

Complement of A181732.

Programs

Magma

[n: n in [1..120]| not IsPrime(90*n+1)]; // Vincenzo Librandi, Jun 09 2017

Mathematica

Select[Range[200], !PrimeQ[90 # + 1] &] (* Vincenzo Librandi, Jun 09 2017 *)