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 A192988 #15 Nov 30 2019 09:14:32
%S A192988 1,2,3,4,9,21,91,1517,385318,24745571498,102057218155974827415,
%T A192988 1735945962956039658808082636319818286550
%N A192988 Smallest number whose representation requires n pentagonal numbers with greedy algorithm.
%F A192988 a(n+1) = ceiling(a(n)/3)*(3*ceiling(a(n)/3)-1)/2 + a(n), a(1) = 1.
%e A192988 a(7)=91 since 91 = 70 + 12 + 5 + 1 + 1 + 1 + 1.
%t A192988 a[1] = 1; a[n_] := a[n] = Ceiling[a[n - 1]/3]*(3*Ceiling[a[n - 1]/3] - 1)/2 + a[n - 1]; Table[a[n], {n, 15}] (* _T. D. Noe_, Jul 13 2011 *)
%Y A192988 Cf. A145172.
%K A192988 nonn
%O A192988 1,2
%A A192988 _Franz Vrabec_, Jul 13 2011