OFFSET
0,2
COMMENTS
Can be thought of as the second sequence of a family: the first is A091137, the third starts 1, 2, 84, 168.
FORMULA
a(n+1) = a(n)*A027760(n+3).
EXAMPLE
The first differences of A141045(2,.) are 11-(-19)=30 and -19-11 = -30. The 2nd difference is a(2)= -30-30= -60.
MATHEMATICA
a[n_] := a[n] = a[n-1]*If[OddQ[n], 2, Denominator[BernoulliB[n+2]]]; a[0]=-1; Table[a[n], {n, 0, 18}] (* Jean-François Alcover, Dec 17 2014 *)
PROG
(PARI) a(n)=if(n, my(pr=a(n-1)); fordiv(n+2, d, if(isprime(d+1), pr*=d+1)); pr, -1) \\ Charles R Greathouse IV, Jul 08 2011
CROSSREFS
KEYWORD
sign
AUTHOR
Paul Curtz, Aug 01 2008
EXTENSIONS
Edited and extended by R. J. Mathar, Aug 12 2008
STATUS
approved