A015917 Numbers k such that sigma(k) + 12 = sigma(k+12).

5, 7, 11, 17, 19, 29, 31, 41, 47, 59, 61, 65, 67, 71, 89, 97, 101, 127, 137, 139, 151, 167, 170, 179, 181, 199, 209, 211, 227, 229, 239, 251, 257, 269, 271, 281, 337, 347, 367, 389, 397, 409, 419, 421, 431, 449, 467, 479, 487, 491, 509, 557, 587

Offset: 1

Author

Robert G. Wilson v

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000203.

Union of A046133 and A054902.

Programs

Mathematica

Select[Range[600],DivisorSigma[1,#]+12==DivisorSigma[1,#+12]&] (* Harvey P. Dale, Oct 14 2012 *)

PARI

is(n)=sigma(n)+12==sigma(n+12) \\ Charles R Greathouse IV, Mar 09 2014