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 A345339 #27 Dec 08 2024 16:07:48
%S A345339 20,38,56,74,92,110,128,146,164,182,200,218,236,254,272,290,308,326,
%T A345339 344,362,380,398,416,434,452,470,488,506,524,542,560,578,596,614,632,
%U A345339 650,668,686,704,722,740,758,776,794,812,830,848,866,884,902,920,938,956,974,992,1010
%N A345339 a(n) = 18*n + 20.
%C A345339 The largest even integer which cannot be written as the sum of 2n composite odd integers, for n >= 1, is 18*n + 20, proved by the Shippensburg University Mathematical Problem Solving Group (see Links).
%H A345339 Ronald E. Ruemmler, <a href="http://www.jstor.org/stable/2689772">Problem 1328</a>, Mathematics Magazine, Vol. 62, No. 4 (October 1989), p. 274; <a href="http://www.jstor.org/stable/2690953">Sums of Composite Odd Numbers</a>, Solution to problem 1328 by Garrett R. Vargas, ibid., Vol. 63, No. 4 (October 1990), pp. 276-277.
%H A345339 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A345339 a(n) = 18*n + 20.
%F A345339 G.f.: 2*(10 - x)/(1 - x)^2. - _Stefano Spezia_, Jun 14 2021
%F A345339 From _Elmo R. Oliveira_, Dec 08 2024: (Start)
%F A345339 E.g.f.: 2*exp(x)*(10 + 9*x).
%F A345339 a(n) = 2*a(n-1) - a(n-2) for n >= 2. (End)
%e A345339 For n = 1, a(1) = A118081(14) = 38.
%t A345339 Table[18*n + 20, {n, 0, 55}] (* _Amiram Eldar_, Jun 14 2021 *)
%t A345339 LinearRecurrence[{2,-1},{20,38},60] (* _Harvey P. Dale_, Jan 15 2023 *)
%Y A345339 Cf. A076770, A118081, A284787, A284788.
%K A345339 nonn,easy
%O A345339 0,1
%A A345339 _Bernard Schott_, Jun 14 2021