OFFSET
1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..300
FORMULA
a(n) = abs(numerator(Sum_{i=1..n} (-1)^i * i/prime(i))).
a(n) = abs(Sum_{i=1..n} ((i(-1)^i * (Product_{k=1..n} prime(k)))/prime(i))). - Petr Platais, Aug 14 2022
MATHEMATICA
Abs[Numerator[Table[Sum[(-1)^i*i/Prime[i], {i, 1, n}], {n, 1, 20}]]]
Abs[Table[Sum[(m*(-1)^m*Product[Prime[n], {n, 1, k}])/Prime[m], {m, 1, k}], {k, 1, 20}]] (* Petr Platais, Aug 11 2022 *)
PROG
(PARI) for(n=1, 20, print1(numerator(abs(sum(k=1, n, (-1)^k*k/prime(k)))), ", ")) \\ G. C. Greubel, Aug 23 2018
(Magma) [Numerator(Abs((&+[(-1)^k*k/NthPrime(k): k in [0..n]]))): n in [1..20]]; // G. C. Greubel, Aug 23 2018
CROSSREFS
KEYWORD
frac,nonn
AUTHOR
Alexander Adamchuk, Jul 01 2006
STATUS
approved