A077017 a(1) = 2, a(n+1) = smallest positive integer divisible by the n-th prime that also has a nontrivial common divisor with a(n).

2, 2, 6, 10, 14, 22, 26, 34, 38, 46, 58, 62, 74, 82, 86, 94, 106, 118, 122, 134, 142, 146, 158, 166, 178, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454, 458, 466, 478, 482, 502, 514

Offset

1,1

Comments

Each term of the sequence is a solution of the equation sigma(x)=3*(x-phi(x)) (*) - the proof is easy. Does there exist a solution of (*) which is not in the sequence? - Farideh Firoozbakht, Apr 22 2006

Links

Table of n, a(n) for n=1..56.

Formula

a(n)=2*prime(n-1) for n>2. - Farideh Firoozbakht, Apr 22 2006

Mathematica

Join[{2, 2}, 2*Prime[Range[2, 60]]] (* Harvey P. Dale, Feb 24 2013 *)

Crossrefs

Sequence in context: A197218 A080460 A080456 * A181551 A362934 A127404

Adjacent sequences: A077014 A077015 A077016 * A077018 A077019 A077020

Keyword

nonn,easy

Author

Amarnath Murthy, Oct 28 2002

Extensions

Corrected and extended by Dean Hickerson, Jan 28 2003

Status

approved