A249416 a(n) = core(Sum_{i=0,...,n} core(binomial(n,i))), where core(n) = A007913(n).

1, 2, 1, 2, 10, 2, 1, 2, 118, 19, 519, 2, 635, 370, 829, 1333, 8454, 17315, 3599, 15307, 423769, 852006, 495431, 2, 2425755, 2121070, 3192295, 1614598, 35685686, 10081687, 735961, 12902173, 216093318, 151123623, 5270424935, 39937013, 22884337, 7281379334

Offset: 0

Author

Vladimir Shevelev, Oct 28 2014

Keywords

• nonn

Crossrefs

Cf. A007913, A248470, A248473, A249388.

Programs

Mathematica

a7913[n_]:=a7913[n]=Times@@(#[[1]]^Mod[#[[2]],2])&[Transpose[FactorInteger[n]]];
Map[a7913[Total[Map[a7913,Binomial[#,Range[0,#]]]]]&,Range[0,50]] (* Peter J. C. Moses, Oct 28 2014 *)

PARI

a(n) = core(sum(i=0, n, core(binomial(n,i)))); \\ Michel Marcus, Nov 13 2014

Extensions

More terms from Peter J. C. Moses, Oct 28 2014