This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A225070 #9 Nov 12 2014 10:34:02 %S A225070 10,69300,9729720,4257000,967412160,4104100000,1408951239696000, %T A225070 59860503846000000,1542547619019487080000,39054496014386012160000, %U A225070 450510331438947780000000 %N A225070 Least decagonal (10-gonal) number that is the product of n decagonal numbers greater than 1. %H A225070 Lars Blomberg, <a href="/A225070/a225070.txt">Table of n, a(n) with solutions for n=1..11</a> %e A225070 Let dec(n) = n*(4n-3). Then %e A225070 a(1) = 10 = dec(2). %e A225070 a(2) = 69300 = dec(132) = dec(2) * dec(42). %e A225070 a(3) = 9729720 = dec(1560) = dec(3) * dec(4) * dec(42). %e A225070 a(4) = 4257000 = dec(1032) = dec(2)^3 * dec(33). %e A225070 a(5) = 967412160 = dec(15552) = dec(2) * dec(3) * dec(4) * dec(8) * dec(9). %e A225070 a(6) = 4104100000 = dec(32032) = dec(2)^3 * dec(4) * dec(7) * dec(11). %Y A225070 Cf. A001107 (decagonal numbers). %Y A225070 Cf. A212616, A212617, A225066-A225069 (3-, 5- to 9-gonal cases). %K A225070 nonn,more %O A225070 1,1 %A A225070 _T. D. Noe_, May 01 2013 %E A225070 Corrected a(6) and added a(7)-a(11) by _Lars Blomberg_, Sep 20 2013