A225067 - OEIS

%I #6 Sep 21 2013 07:30:20

%S 7,6426,35224,2077992,3610893055,14209771072,118896888880,

%T 6400213601782,22535310978496008,22535310978496008,

%U 2418562185097611420000,2462278542548750181849600

%N Least heptagonal (7-gonal) number that is the product of n heptagonal numbers greater than 1.

%H Lars Blomberg, <a href="/A225067/a225067.txt">Table of n, a(n) with solutions for n=1..12</a>

%e Let hep(n) = n*(5n-3)/2. Then

%e a(1) = 7 = hep(2).

%e a(2) = 6426 = hep(51) = hep(4) * hep(9).

%e a(3) = 35224 = hep(119) = hep(2) * hep(4) * hep(8).

%e a(4) = 2077992 = hep(912) = hep(2)^2 * hep(3) * hep(31).

%e a(5) = 3610893055 = hep(38005) = hep(2)^3 * hep(5) * hep(277).

%e a(6) = 14209771072 = hep(75392) = hep(2)^4 * hep(31) * hep(32).

%Y Cf. A000566 (heptagonal numbers).

%Y Cf. A212616, A212617, A225066-A225070 (3-, 5- to 10-gonal cases).

%K nonn,more

%O 1,1

%A _T. D. Noe_, May 01 2013

%E Corrected a(6) and added a(7)-a(12) by _Lars Blomberg_, Sep 21 2013