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A049286 Triangle of partitions v(d,c) defined in A002572. 2
1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 5, 4, 2, 1, 1, 9, 7, 4, 2, 1, 1, 16, 12, 7, 4, 2, 1, 1, 28, 22, 13, 7, 4, 2, 1, 1, 50, 39, 24, 13, 7, 4, 2, 1, 1, 89, 70, 42, 24, 13, 7, 4, 2, 1, 1, 159, 126, 76, 43, 24, 13, 7, 4, 2, 1, 1, 285, 225, 137, 78, 43, 24, 13, 7, 4, 2, 1, 1, 510 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,4

REFERENCES

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.

LINKS

Table of n, a(n) for n=1..79.

Shimon Even & Abraham Lempel, Generation and enumeration of all solutions of the characteristic sum condition, Information and Control 21 (1972), 476-482.

EXAMPLE

1; 1,1; 2,1,1; 3,2,1,1; 5,4,2,1,1; 9,7,4,2,1,1; ...

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;

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}]]]; Table[v[d, c], {c, 1, 13}, {d, 1, c}] // Flatten (* Jean-Fran├žois Alcover, Dec 10 2012, after Maple *)

CROSSREFS

Cf. A002572, A002573, A002574, A049284, A049285. See A047913 for another version.

Sequence in context: A175331 A098805 A168396 * A308477 A079216 A181654

Adjacent sequences:  A049283 A049284 A049285 * A049287 A049288 A049289

KEYWORD

nonn,tabl,nice,easy

AUTHOR

N. J. A. Sloane, Michael Somos

STATUS

approved

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Last modified August 21 05:32 EDT 2019. Contains 326162 sequences. (Running on oeis4.)