A063515 Sum of divisors of Woodall (or Riesel) numbers; sigma(A003261(n)); sigma(n*2^n - 1).

1, 8, 24, 104, 216, 384, 1080, 2160, 4896, 13656, 32552, 51312, 137160, 287408, 573600, 1999872, 3034368, 4778400, 11098080, 20984560, 49533120, 137218560, 294000768, 417361152, 958698064, 1755253280, 4362821232, 10552800000

Offset: 1

Author

Jason Earls, Jul 31 2001

Keywords

• easy
• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..853 (terms 1..200 from Harry J. Smith)

Crossrefs

Cf. A000203, A003261.

Programs

PARI

j=[]; for(n=1,50,x=sigma(n*2^n-1); j=concat(j,x)); j

PARI

{ for (n=1, 200, write("b063515.txt", n, " ", sigma(n*2^n - 1)) ) } \\ Harry J. Smith, Aug 24 2009

Formula

a(n) = sigma(n*2^n-1).