A160048 Numerator of the Harary number for the path graph P_n.

0, 2, 5, 26, 77, 87, 223, 962, 4609, 4861, 55991, 58301, 785633, 811373, 835397, 3431678, 29889983, 30570663, 197698279, 201578155, 41054655, 13920029, 325333835, 990874363, 25128807667, 25472027467, 232222818803, 235091155703

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

Eric Weisstein's World of Mathematics, Harary Index

Example

0, 2, 5, 26/3, 77/6, 87/5, 223/10, 962/35, 4609/140, 4861/126, ...

Prog

(PARI)
harmonic(n)=sum(k=1, n, 1/k);
a(n)=numerator(2*n*(harmonic(n)-1)); \\ Andrew Howroyd, Oct 31 2017

Crossrefs

Cf. A160049, A027612.

Sequence in context: A008318 A365324 A204275 * A019047 A221679 A178390

Adjacent sequences: A160045 A160046 A160047 * A160049 A160050 A160051

Keyword

nonn,frac

Author

Eric W. Weisstein, Apr 30 2009

Status

approved