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 A227365 #17 May 04 2021 07:37:33 %S A227365 0,1,2,5,14,62,68,104,398,3086,3096,3196,4406,20246,243326,243341, %T A227365 243566,247406,316766,1638686,28150526,28150547,28150988,28161152, %U A227365 28405550,34526126,193916126,4503821726,4503821754,4503822538,4503846086,4504576886,4527986846,5301270686 %N A227365 a(n) = 0 + 1*2 + 3*4*5 + 6*7*8*9 + ... + ...*n. %H A227365 Seiichi Manyama, <a href="/A227365/b227365.txt">Table of n, a(n) for n = 0..10000</a> %e A227365 a(4) = 0 + 1*2 + 3*4 = 14. %e A227365 a(5) = 0 + 1*2 + 3*4*5 = 62. %e A227365 a(6) = 0 + 1*2 + 3*4*5 + 6 = 68. %o A227365 (Python) %o A227365 for n in range(55): %o A227365 sum = i = 0 %o A227365 k = 1 %o A227365 while i<=n: %o A227365 product = 1 %o A227365 for x in range(k): %o A227365 product *= i %o A227365 i += 1 %o A227365 if i>n: break %o A227365 sum += product %o A227365 k += 1 %o A227365 print(str(sum), end=',') %Y A227365 Cf. A227363, A227364, A227366, A227367. %K A227365 nonn %O A227365 0,3 %A A227365 _Alex Ratushnyak_, Jul 07 2013