# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/

Search: id:a250345
Showing 1-1 of 1

%I A250345 #5 Nov 19 2014 10:42:59
%S A250345 1,7,378,4284,294525,3180870,59376240,2510766720,2824612560,
%T A250345 147507544800,2109357890640,43721236278720,1468304851693680,
%U A250345 105943842376051680,113511259688626800,121078677001201920,5274489866864858640,161957865323732718240,3931977063692844326160
%N A250345 Numerator of the harmonic mean of the first n heptagonal numbers.
%H A250345 Colin Barker, <a href="/A250345/b250345.txt">Table of n, a(n) for n = 1..850</a>
%e A250345 a(3) = 378 because the first 3 heptagonal numbers are [1,7,18], and 3/(1/1+1/7+1/18) = 378/151.
%o A250345 (PARI)
%o A250345 harmonicmean(v) = #v / sum(k=1, #v, 1/v[k])
%o A250345 s=vector(30); for(n=1, #s, s[n]=numerator(harmonicmean(vector(n, k, k*(5*k-3)/2)))); s
%Y A250345 Cf. A000566 (heptagonal numbers), A247115 (denominators).
%K A250345 nonn
%O A250345 1,2
%A A250345 _Colin Barker_, Nov 19 2014

# Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE