|
%I #11 Jun 11 2021 09:47:43
%S 1,1,3,7,41,3,53,437,5167,34189,36037,3833,3987,11521,274223,3458639,
%T 103063291,100392623,34273501,33510453,308270747,302107667,
%U 12626774467,12402802537,25216220279,124110148411,2142721739387,111888942151111
%N a(n) = numerator(Sum_{k=1..n} (-1)^(k+1)/(prime(k)-1)).
%C Numbers m such that A128648(m) = A128646(n) are listed in A128649.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PrimeSums.html">Prime sums</a>
%F a(n) = numerator(Sum_{k=1..n} (-1)^(k+1)/(prime(k)-1)).
%t Table[Numerator[Sum[(-1)^(k+1)*1/(Prime[k]-1),{k,1,n}]],{n,1,36}]
%Y Cf. A128648 (denominator(Sum_{k=1..n} (-1)^(k+1)/(prime(k)-1))).
%Y Cf. A120271 (numerator(Sum_{k=1..n} 1/(prime(k)-1))).
%Y Cf. A128646, A128649, A119686, A006093, A000040.
%K frac,nonn
%O 1,3
%A _Alexander Adamchuk_, Mar 18 2007
|
