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1,4
Table of n, a(n) for n=1..62.
a(7^k)=(49^k-1)/16
(PARI) a(n)=sum(k=1, n, -sum(i=1, k-1, (-1)^i*7^valuation(i, 7)))
Sequence in context: A195952 A236545 A095060 * A097365 A156906 A216245
Adjacent sequences: A094114 A094115 A094116 * A094118 A094119 A094120
nonn
Benoit Cloitre, May 03 2004
approved