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A066766 Decimal expansion of Sum_{k>=1} sigma(k)/2^k where sigma(k) is the sum of divisors of k, 1 <= d <= k. 2
2, 7, 4, 4, 0, 3, 3, 8, 8, 8, 7, 5, 9, 4, 8, 8, 3, 6, 0, 4, 8, 0, 2, 1, 4, 8, 9, 1, 4, 9, 2, 2, 7, 2, 1, 6, 4, 3, 1, 1, 4, 2, 8, 9, 8, 1, 3, 1, 9, 6, 3, 9, 3, 1, 7, 8, 4, 8, 5, 2, 8, 8, 8, 4, 7, 3, 7, 9, 1, 2, 2, 8, 3, 2, 6, 3, 8, 9, 5, 6, 8, 8, 5, 6, 6, 2, 5, 2, 3, 1, 0, 7, 1, 2, 5, 0, 6, 8, 8, 7, 7, 3, 7, 4, 0 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

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

LINKS

Table of n, a(n) for n=1..105.

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

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

EXAMPLE

c = 2.74403388875948836048021489149227216431142898131963931784...

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) suminf(k=1, sigma(k)/2^k) \\ Michel Marcus, Apr 27 2018

CROSSREFS

Cf. A066772.

Sequence in context: A092943 A196501 A292819 * A241517 A145433 A055200

Adjacent sequences:  A066763 A066764 A066765 * A066767 A066768 A066769

KEYWORD

nonn,cons

AUTHOR

Randall L. Rathbun, Jan 16 2002

EXTENSIONS

Name corrected by Paul D. Hanna, Apr 26 2018

STATUS

approved

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Last modified October 14 14:39 EDT 2019. Contains 328019 sequences. (Running on oeis4.)