

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
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OFFSET

1,1


REFERENCES

S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 354361.


LINKS

Table of n, a(n) for n=1..105.
S. R. Finch, Digital Search Tree Constants


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



