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
KEYWORD
nonn,frac
AUTHOR
Eric W. Weisstein, Apr 30 2009
STATUS
approved