%I #21 Aug 14 2020 13:47:30

%S 7,26,70,162,336,638,1137,2001,3191,5047,7820,11568,17178

%N a(n) = solution to the postage stamp problem with 7 denominations and n stamps.

%C _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 R. K. Guy, Unsolved Problems in Number Theory, C12.

%H 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 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 M. F. Challis, J. P. Robinson, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL13/Challis/challis6.html">Some extremal postage stamp bases</a>, JIS 13 (2010) #10.2.3.

%H Erich Friedman, <a href="https://erich-friedman.github.io/mathmagic/0403.html">Postage stamp problem</a>

%H 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 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PostageStampProblem.html">Postage stamp problem</a>

%Y Postage stamp sequences: A001208, A001209, A001210, A001211, A001212, A001213, A001214, A001215, A001216, A005342, A005343, A005344, A014616, A053346, A053348, A075060, A084192, A084193.

%K nonn,more

%O 1,1

%A _N. J. A. Sloane_, Jun 20 2003

%E a(9) from Challis by _R. J. Mathar_, Apr 01 2006

%E Entry improved by comments from John Seldon (johnseldon(AT)onetel.com), Sep 15 2004

%E a(10)-a(13) from Challis and Robinson by _Robert Price_, Jul 19 2013