OFFSET
0,5
COMMENTS
Br(n)=0, 1, 1, 1/2, 0, -1/6, 0, 1/6, 0, -3/10, 0, 5/6, 0, -691/210, 0,.. .
a(n) is the numerators of Bp2(n)=0, 0, 0, 1, 2, 5/2, 5/2, 7/3, 7/3, 5/2, 5/2, 11/5, 11/5, 91/30, 91/30,... . Bp2(n) is an autosequence like Br(n).
With possible future sequences we can write the array PB
1, 0, 0, 0, 0, 0, 0, 0, 0,
1, 1, 0, 0, 0, 0, 0, 0, 0,
1, 3/2, 1, 0, 0, 0, 0, 0, 0,
1, 5/3, 2, 1, 0, 0, 0, 0, 0,
1, 5/3, 5/2, 5/2, 1, 0, 0, 0, 0,
1, 49/30, 5/2, 7/2, 3, 1, 0, 0, 0,
1, 49/30, 7/3, 7/2, 14/3, 7/2, 1, 0, 0,
1, 58/35, 7/3, 3, 14/3, 6, 4, 1, 0,
1, 58/35, 5/2, 3, 7/2, 6, 15/2, 9/2, 1, etc.
The first column is A000012. The second A165142(n+1)/(1 followed by A100650(n)). The third is Bp2(n+1). The next others are built by the same way. From the second,every column is based on A164555(n)/A027642(n).
With negative (2*n+2)-th diagonals,the array without 0's is the triangle NPB. The sum of every row is
1, 0, 1/2, -1/3, 1/3, -11/30, 11/30, -12/35, 12/35, -79/210, 79/210,... .
EXAMPLE
a(0)=a(1)=0, a(i)=numerators of 0+Br(0)=0, 0+Br(1)=1, 1+Br(2)=2, 2+Br(3)=5/2, 5/2+Br(4)=5/2,... .
MATHEMATICA
nmax = 30; Br[0] = 0; Br[1] = Br[2] = 1; Br[n_] := Numerator[2*n*BernoulliB[n-1]] / Denominator[n*BernoulliB[n-1]]; Bp2 = Join[{0, 0}, Table[Br[n], {n, 0, nmax-2}] // Accumulate]; a[n_] := Numerator[Bp2[[n+1]]]; Table[a[n], {n, 0, nmax}] (* Jean-François Alcover, Dec 18 2013 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Paul Curtz, Dec 13 2013
EXTENSIONS
a(17)-a(30) from Jean-François Alcover, Dec 18 2013
STATUS
approved