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 A097940 #19 Oct 15 2024 17:16:36 %S A097940 1,4,8,20,37,86,173,372,788,1680,3550,7554,15994,33820,71374,150376, %T A097940 316151,663474,1389760,2906116,6066899,12645608,26318870,54700044, %U A097940 113536171,235363832,487342781,1007969620,2082597193,4298660754,8864505305,18263797648,37597869188 %N A097940 Sum of smallest parts (counted with multiplicity) of all compositions of n. %H A097940 Alois P. Heinz, <a href="/A097940/b097940.txt">Table of n, a(n) for n = 1..1000</a> %H A097940 Knopfmacher, Arnold; Munagi, Augustine O. <a href="https://doi.org/10.1007/978-3-642-30979-3_11">Smallest parts in compositions</a>, Kotsireas, Ilias S. (ed.) et al., Advances in combinatorics. 3rd Waterloo workshop on computer algebra (WWCA, W80) 2011, Waterloo, Canada, May 26-29, 2011. Berlin: Springer. 197-207 (2013). %F A097940 G.f.: (1-x)^2 * Sum_{k>=1} k*x^k/(1-x-x^k)^2. %F A097940 a(n) ~ n * 2^(n-3). - _Vaclav Kotesovec_, Sep 05 2014 %F A097940 a(n) = Sum_{k=1..n} A308630(n,k). - _R. J. Mathar_, Jun 12 2019 %t A097940 Drop[ CoefficientList[ Series[(1 - x)^2*Sum[k*x^k/(1 - x - x^k)^2, {k, 50}], {x, 0, 30}], x], 1] (* _Robert G. Wilson v_, Sep 08 2004 *) %Y A097940 Cf. A046746, A092309. %K A097940 easy,nonn %O A097940 1,2 %A A097940 _Vladeta Jovovic_, Sep 05 2004 %E A097940 More terms from _Robert G. Wilson v_, Sep 08 2004