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A001211 a(n) is the solution to the postage stamp problem with 6 denominations and n stamps.

%I A001211 M4136 N1836 #40 Feb 16 2025 08:32:22
%S A001211 6,20,52,108,211,388,664,1045,1617,2510,3607,5118,7066,9748,12793,
%T A001211 17061,22342,28874,36560,45745,57814,72997,87555,106888,129783
%N A001211 a(n) is the solution to the postage stamp problem with 6 denominations and n stamps.
%C A001211 _Fred Lunnon_ [W. F. Lunnon] defines "solution" to be the smallest value not obtainable by the best set of stamps. The solutions given are one lower than this, that is, the sequence gives the largest number obtainable without a break using the best set of stamps.
%D A001211 R. K. Guy, Unsolved Problems in Number Theory, C12.
%D A001211 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D A001211 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A001211 R. Alter and J. A. Barnett, <a href="http://www.jstor.org/stable/2321610">A postage stamp problem</a>, Amer. Math. Monthly, 87 (1980), 206-210.
%H A001211 M. F. Challis, <a href="http://dx.doi.org/10.1093/comjnl/36.2.117">Two new techniques for computing extremal h-bases A_k</a>, Comp. J. 36(2) (1993) 117-126.
%H A001211 M. F. Challis and J. P. Robinson, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL13/Challis/challis6.html">Some Extremal Postage Stamp Bases</a>, J. Integer Seq., 13 (2010), Article 10.2.3.
%H A001211 Erich Friedman, <a href="https://erich-friedman.github.io/mathmagic/0403.html">Postage stamp problem</a>
%H A001211 W. F. Lunnon, <a href="https://doi.org/10.1093/comjnl/12.4.377">A postage stamp problem</a>, Comput. J. 12 (1969) 377-380.
%H A001211 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PostageStampProblem.html">Postage stamp problem</a>
%Y A001211 Postage stamp sequences: A001208, A001209, A001210, A001211, A001212, A001213, A001214, A001215, A001216, A005342, A005343, A005344, A014616, A053346, A053348, A075060, A084192, A084193.
%Y A001211 A row or column of the array A196416 (possibly with 1 subtracted from it).
%K A001211 nonn,more
%O A001211 1,1
%A A001211 _N. J. A. Sloane_
%E A001211 a(11)-a(15) from Challis added by _R. J. Mathar_, Apr 01 2006
%E A001211 Entry improved by comments from John Seldon (johnseldon(AT)onetel.com), Sep 15 2004
%E A001211 a(16)-a(25) from Challis and Robinson added by John P Robinson (john-robinson(AT)uiowa.edu), Feb 18 2010