A066772 Continued fraction expansion for Sum_{k>=1} d(k)/2^k where d(k) are divisors of k, 1 <= d <= k.

2, 1, 2, 1, 9, 1, 2, 1, 1, 1, 5, 8, 1, 3, 2, 3, 2, 2, 2, 2, 1, 3, 3, 4, 12, 1, 1, 1, 11, 4, 15, 6, 3, 3, 2, 1, 20, 4, 4, 1, 4, 1, 2, 1, 2, 6, 1, 2, 1, 28, 107, 1, 4, 4, 3, 1, 2, 2, 4, 2, 3, 51, 1, 1, 1, 4, 2, 4, 1, 20, 20, 1, 14, 3, 27, 1, 4, 3, 14, 329, 1, 1, 1, 111, 2, 3, 1, 2, 1, 4, 1, 6, 1, 4, 1

Offset

0,1

Comments

A(1669) accurate to 500 decimal digits.

References

Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 354-361.

Links

Table of n, a(n) for n=0..94.

Steven R. Finch, Digital Search Tree Constants [Broken link]

Steven R. Finch, Digital Search Tree Constants [From the Wayback machine]

Prog

(PARI) {smv(v)= s=0; for(i=1, matsize(v)[2], s=s+v[i]); s }
{A066766(n)= sm=0; for(j=1, n, sm=sm+smv(divisors(j)/2^j)); sm*1.0 }
(PARI) contfrac(suminf(k=1, sigma(k)/2^k)) \\ Michel Marcus, Apr 25 2022

Crossrefs

Cf. A066766 (decimal expansion).

Sequence in context: A201453 A260897 A342920 * A104060 A062347 A124781

Adjacent sequences: A066769 A066770 A066771 * A066773 A066774 A066775

Keyword

nonn,cofr,changed

Author

Randall L Rathbun, Jan 16 2002

Extensions

Offset changed by Andrew Howroyd, Jul 04 2024

Status

approved