A046826 Denominator of Sum_{k=0..n} 1/binomial(n,k).

1, 1, 2, 3, 3, 5, 60, 105, 35, 63, 630, 1155, 6930, 12870, 24024, 9009, 9009, 17017, 306306, 2909907, 692835, 1322685, 58198140, 111546435, 66927861, 128707425, 371821450, 717084225, 20078358300, 38818159380, 2329089562800, 4512611027925

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy
• frac
• nice

Examples

			1, 2, 5/2, 8/3, 8/3, 13/5, 151/60, 256/105, 83/35, 146/63, 1433/630, 2588/1155, 15341/6930, 28211/12870, 52235/24024, 19456/9009, 19345/9009, ... = A046825/A046826
		

References

• See A046825, which is the main entry.

Links

• T. D. Noe, Table of n, a(n) for n=0..200

Crossrefs

Cf. A003149, A046825.

Programs

Magma

[Denominator((&+[1/Binomial(n,j): j in [0..n]])): n in [0..40]]; // G. C. Greubel, May 24 2021

Mathematica

Denominator[Table[Sum[1/Binomial[n,k],{k,0,n}],{n,0,40}]] (* Harvey P. Dale, Nov 05 2011 *)

Sage

[denominator(sum(1/binomial(n,j) for j in (0..n))) for n in (0..40)] # G. C. Greubel, May 24 2021

Formula

a(n) = denominator( A003149(n)/n! ). - G. C. Greubel, May 24 2021