A086540 Numbers n such that n and n+1 both are members of A074997; i.e., on the one hand n-1 and n+1 have the same prime signature, on the other hand n and n+2 have the same prime signature.

18, 55, 248, 340, 348, 722, 850, 949, 1061, 1148, 1204, 1205, 1241, 1277, 1314, 1315, 1667, 1672, 2148, 2716, 2948, 2949, 3258, 3581, 3650, 3651, 4044, 4265, 4627, 4842, 5092, 5093, 5451, 5741, 5765, 6244, 6355, 6356, 6565, 6640, 6851, 6963, 7362, 7404

Offset: 1

Author

Amarnath Murthy, Aug 22 2003

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A074997.

Programs

PARI

isok1(n) = vecsort(factor(n-1)[,2]) == vecsort(factor(n+1)[,2]);
isok(n) = isok1(n) && isok1(n+1); \\ Michel Marcus, Jul 28 2015

Extensions

More terms from David Wasserman, Mar 21 2005