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A073099
Numerator of b(n) = n * Sum_{k=2^n..2^(n+1)-1} (-1)^k/k.
4
1, 31, 12307, 1180906852403, 4726403852635437852230311, 26387151472737581442533784610190235872453672267436617, 16379090991119093215568426722482532968867795792384100101494022155108529793899838205018451949281878220687877
OFFSET
1,2
LINKS
G. Vacca, A new series for the Eulerian constant gamma=.577..., Quart. J. Pure Appl. Math., Vol. 41 (1910), pp. 363-368.
FORMULA
Sum_{k>=1} b(k) = gamma = 0.5772... (A001620).
EXAMPLE
The fractions begin with 1/6, 31/210, 12307/120120, 1180906852403/18050444111700, ...
MATHEMATICA
a[n_] := Numerator[n * Sum[(-1)^k/k, {k, 2^n, 2^(n+1)-1}]]; Array[a, 7] (* Amiram Eldar, May 19 2022 *)
PROG
(PARI) a(n)=numerator( n*sum(k=2^n, 2^(n+1)-1, (-1)^k/k))
CROSSREFS
Cf. A001620, A073100 (denominators).
Sequence in context: A261947 A069451 A374668 * A245571 A074218 A161395
KEYWORD
easy,frac,nonn
AUTHOR
Benoit Cloitre, Aug 18 2002
STATUS
approved