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A001213 a(n) = solution to the postage stamp problem with n denominations and 3 stamps.
(Formerly M2647 N1340)
3, 7, 15, 24, 36, 52, 70, 93, 121, 154, 186, 225, 271, 323, 385, 450, 515, 606, 684, 788, 865, 977, 1091, 1201, 1361 (list; graph; refs; listen; history; text; internal format)



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.


R. Alter and J. A. Barnett, A postage stamp problem, Amer. Math. Monthly, 87 (1980), 206-210.

R. L. Graham and N. J. A. Sloane, On Additive Bases and Harmonious Graphs, SIAM J. Algebraic and Discrete Methods, 1 (1980), 382-404.

R. K. Guy, Unsolved Problems in Number Theory, C12.

W. F. Lunnon, A postage stamp problem. Comput. J. 12 (1969) 377-380.

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

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


Table of n, a(n) for n=1..25.

Erich Friedman, Postage stamp problem

R. L. Graham and N. J. A. Sloane, On Additive Bases and Harmonious Graphs

Eric Weisstein's World of Mathematics, Postage stamp problem


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

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

Sequence in context: A284090 A283865 A283607 * A114221 A226471 A175510

Adjacent sequences:  A001210 A001211 A001212 * A001214 A001215 A001216




N. J. A. Sloane.


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

More terms from Al Zimmermann, Feb 20 2002

Further terms from Friedman web site, Jun 20, 2003

Removed a(17), as it was incorrect. Al Zimmermann, Nov 08 2009

a(17)-a(25) from Friedman by Robert Price, Jul 19 2013



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Last modified March 26 17:03 EDT 2017. Contains 284137 sequences.