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A001213 a(n) is the solution to the postage stamp problem with n denominations and 3 stamps.
(Formerly M2647 N1340)
21

%I M2647 N1340 #35 Feb 03 2022 02:28:02

%S 3,7,15,24,36,52,70,93,121,154,186,225,271,323,385,450,515,606,684,

%T 788,865,977,1091,1201,1361

%N a(n) is the solution to the postage stamp problem with n denominations and 3 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.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

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

%H R. L. Graham and N. J. A. Sloane, <a href="http://dx.doi.org/10.1137/0601045">On Additive Bases and Harmonious Graphs</a>, SIAM J. Algebraic and Discrete Methods, 1 (1980), 382-404.

%H R. L. Graham and N. J. A. Sloane, <a href="http://neilsloane.com/doc/RLG/073.pdf">On Additive Bases and Harmonious Graphs</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.

%Y A row or column of the array A196416 (possibly with 1 subtracted from it).

%K nonn,more

%O 1,1

%A _N. J. A. Sloane_

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

%E More terms from _Al Zimmermann_, Feb 20 2002

%E Further terms from Friedman web site, Jun 20 2003

%E Incorrect value of a(17) removed by _Al Zimmermann_, Nov 08 2009

%E a(17)-a(25) from Friedman added by _Robert Price_, Jul 19 2013

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Last modified April 17 21:01 EDT 2024. Contains 371767 sequences. (Running on oeis4.)