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 A091572 #14 Jan 30 2018 18:57:36
%S A091572 8,14,20,26,34,40,48,54,62,66,74,80,90,94,102,106,116,120,130,134,144,
%T A091572 146,156,160,172,174,184,186,198,200,212,214,226,226,238,240,254,254,
%U A091572 266,266,280,280,294,294,308,306,320,320,336,334,348,346,362,360,376
%N A091572 Poincaré series [or Poincare series] of the preprojective algebra of an extended Dynkin diagram of type E_7.
%D A091572 I, Reiten, Dynkin diagrams and the representation theory of algebras, Notices of the AMS, Vol. 44, No 5.
%F A091572 a(n) = 6*(n+1) + 2*A087504(n).
%F A091572 G.f.: (6/(1-x)^2)+2*(1-x^9)/((1-x^4)*(1-x^6)*(1-x)).
%t A091572 CoefficientList[ Series[ (8 + 6x + 6x^2 + 14x^3 + 6x^4 + 6x^5 + 8x^6) / (1 - x + x^3 - 2x^4 + x^5 - x^7 + x^8),{x,0,54}],x] (* _Jean-François Alcover_, Dec 02 2011 *)
%Y A091572 Cf. A087504, A091571, A091573, A091574, A091575, A091576, A091577.
%K A091572 easy,nonn
%O A091572 0,1
%A A091572 _Paul Boddington_, Jan 22 2004