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A001208
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a(n) = solution to the postage stamp problem with 3 denominations and n stamps.
(Formerly M2721 N1351)
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22
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3, 8, 15, 26, 35, 52, 69, 89, 112, 146, 172, 212, 259, 302, 354, 418, 476, 548, 633, 714, 805, 902, 1012, 1127, 1254, 1382, 1524, 1678, 1841, 2010, 2188, 2382, 2584, 2801, 3020, 3256, 3508, 3772, 4043, 4326, 4628, 4941, 5272, 5606, 5960, 6334, 6723, 7120
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| 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.
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REFERENCES
| R. Alter and J. A. Barnett, A postage stamp problem, Amer. Math. Monthly, 87 (1980), 206-210.
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).
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LINKS
| M. F. Challis, Two new techniques for computing extremal h-bases A_kComp. J. 36(2) (1993) 117-126.
Erich Friedman, Postage stamp problem
Eric Weisstein's World of Mathematics, Postage stamp problem
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MAPLE
| c2 :=array(0..8, [3, 3, 5, 5, 7, 6, 8, 8, 10]) ; c3 :=array(0..8, 1..2, [[1, 1], [1, 1], [2, 1], [2, 1], [3, 1], [2, 2], [3, 2], [3, 2], [4, 2]]); c4 :=array(0..8, 1..3, [[0, 0, 0], [0, 0, 1], [1, 0, 1], [1, 0, 2], [2, 0, 2], [2, 1, 2], [3, 1, 2], [3, 1, 3], [4, 1, 3]]) ; for n from 23 to 100 do r := n mod 9 ; t := iquo(n, 9) ; a2 := 6*t+c2[r] ; a3 := (2*t+c3[r, 1])+(2*t+c3[r, 2])*a2 ; printf("%a, ", 4*t+c4[r, 1]+(2*t+c4[r, 2])*a2+(3*t+c4[r, 3])*a3) ; end: - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 01 2006
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MATHEMATICA
| ClearAll[c2, c3, c4, a]; Evaluate[ Array[c2, 9, 0]] = {3, 3, 5, 5, 7, 6, 8, 8, 10}; Evaluate[ Array[c3, {9, 2}, {0, 1}]] = {{1, 1}, {1, 1}, {2, 1}, {2, 1}, {3, 1}, {2, 2}, {3, 2}, {3, 2}, {4, 2}}; Evaluate[ Array[c4, {9, 3}, {0, 1}]] = {{0, 0, 0}, {0, 0, 1}, {1, 0, 1}, {1, 0, 2}, {2, 0, 2}, {2, 1, 2}, {3, 1, 2}, {3, 1, 3}, {4, 1, 3}}; Evaluate[ Array[a, 19]] = {3, 8, 15, 26, 35, 52, 69, 89, 112, 146, 172, 212, 259, 302, 354, 418, 476, 548, 633}; a[n_] := (r = Mod[n, 9]; t = Quotient[n, 9]; a2 = 6t + c2[r]; a3 = (2t + c3[r, 1]) + (2t + c3[r, 2])*a2; 4t + c4[r, 1] + (2t + c4[r, 2])*a2 + (3t + c4[r, 3])*a3); Table[a[n], {n, 1, 48}] (* From Jean-François Alcover, Dec 19 2011, after R. J. Mathar's Maple program *)
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CROSSREFS
| Postage stamp sequences: A001208 A001209 A001210 A001211 A001212 A001213 A001214 A001215 A001216 A005342 A005343 A005344 A014616 A053346 A053348 A075060 A084192 A084193
Equals A195618 - 1.
A row or column of the array A196416 (possibly with 1 subtracted from it).
Sequence in context: A022451 A080181 A071399 * A159465 A071148 A172289
Adjacent sequences: A001205 A001206 A001207 * A001209 A001210 A001211
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KEYWORD
| nonn,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Added Maple recursion program valid for n>=23 from Challis. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 01 2006
At least 64 terms are known, see Friedman link.
Entry improved by comments from John Seldon (johnseldon(AT)onetel.com), Sep 15 2004
More terms from Jean Gaumont (jeangaum87(AT)yahoo.com), Apr 16 2006
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