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A128647 a(n) = numerator(Sum_{k=1..n} (-1)^(k+1)/(prime(k)-1)). 3
1, 1, 3, 7, 41, 3, 53, 437, 5167, 34189, 36037, 3833, 3987, 11521, 274223, 3458639, 103063291, 100392623, 34273501, 33510453, 308270747, 302107667, 12626774467, 12402802537, 25216220279, 124110148411, 2142721739387, 111888942151111 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Numbers m such that A128648(m) = A128646(n) are listed in A128649.
LINKS
Eric Weisstein's World of Mathematics, Prime sums
FORMULA
a(n) = numerator(Sum_{k=1..n} (-1)^(k+1)/(prime(k)-1)).
MATHEMATICA
Table[Numerator[Sum[(-1)^(k+1)*1/(Prime[k]-1), {k, 1, n}]], {n, 1, 36}]
CROSSREFS
Cf. A128648 (denominator(Sum_{k=1..n} (-1)^(k+1)/(prime(k)-1))).
Cf. A120271 (numerator(Sum_{k=1..n} 1/(prime(k)-1))).
Sequence in context: A019024 A135071 A096219 * A071730 A058815 A333649
KEYWORD
frac,nonn
AUTHOR
Alexander Adamchuk, Mar 18 2007
STATUS
approved

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Last modified April 22 08:40 EDT 2024. Contains 371893 sequences. (Running on oeis4.)