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A160048
Numerator of the Harary number for the path graph P_n.
2
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
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
Sequence in context: A008318 A365324 A204275 * A019047 A221679 A178390
KEYWORD
nonn,frac
AUTHOR
Eric W. Weisstein, Apr 30 2009
STATUS
approved