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

Author

Amarnath Murthy, Oct 28 2002

Keywords

• nonn
• easy

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

Programs

Mathematica

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

Formula

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

Extensions

Corrected and extended by Dean Hickerson, Jan 28 2003