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A002573
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Restricted partitions.
(Formerly M1062 N0399)
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9
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0, 1, 1, 2, 4, 7, 12, 22, 39, 70, 126, 225, 404, 725, 1299, 2331, 4182, 7501, 13458, 24145, 43316, 77715, 139430, 250152, 448808, 805222, 1444677, 2591958, 4650342, 8343380, 14969239, 26856992, 48185362, 86451602, 155106844
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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REFERENCES
| Even, Shimon; Lempel, Abraham; Generation and enumeration of all solutions of the characteristic sum condition. Information and Control 21 (1972), 476-482.
Minc, H.; A problem in partitions: Enumeration of elements of a given degree in the free commutative entropic cyclic groupoid. Proc. Edinburgh Math. Soc. (2) 11 1958/1959 223-224.
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
| Vincenzo Librandi, Table of n, a(n) for n = 1..500
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MAPLE
| v := proc(c, d) option remember; local i; if d < 0 or c < 0 then 0 elif d = c then 1 else add(v(i, d-c), i=1..2*c); fi; end; [ seq(v(2, n), n=1..50) ];
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MATHEMATICA
| v[c_, d_] := v[c, d] = If[d < 0 || c < 0, 0, If[d == c, 1, Sum[v[i, d - c], {i, 1, 2*c}]]]; a[n_] := v[2, n]; Table[a[n], {n, 1, 35}] (* From Jean-François Alcover, Jan 30 2012, after Maple *)
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CROSSREFS
| Cf. A002572, A047913, A002574, A049284, A049285.
A column of the triangle in A176431.
Sequence in context: A135460 A089259 A026713 * A064492 A000072 A018179
Adjacent sequences: A002570 A002571 A002572 * A002574 A002575 A002576
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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