A063515 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

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

FORMULA

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

PROG

(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

CROSSREFS

Cf. A000203, A003261.

Sequence in context: A334756 A281463 A267326 * A220706 A246030 A010566

Adjacent sequences: A063512 A063513 A063514 * A063516 A063517 A063518

KEYWORD

easy,nonn

AUTHOR

Jason Earls, Jul 31 2001

STATUS

approved