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A005575 a(n) = A259095(2n,n).
(Formerly M1390)
5
0, 0, 1, 2, 5, 11, 20, 37, 63, 110, 174, 283, 435, 671, 1001, 1492, 2160, 3127, 4442, 6269, 8739, 12109, 16597, 22618, 30576, 41077, 54834, 72788, 96056, 126131, 164829, 214327, 277534, 357810, 459507, 587779, 749220, 951473, 1204501, 1519691, 1911618, 2397247, 2997985, 3738482, 4649981, 5768457, 7138640, 8812704, 10854735, 13339286 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
Computed by R. K. Guy in 1988.
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
F. C. Auluck, On some new types of partitions associated with generalized Ferrers graphs, Proc. Cambridge Philos. Soc. 47, (1951), 679-686.
R. K. Guy, Letter to N. J. A. Sloane, Apr 08 1988 (annotated scanned copy, included with permission)
E. M. Wright, Stacks, III, Quart. J. Math. Oxford, 23 (1972), 153-158.
MAPLE
b:= proc(n, i, d) option remember; `if`(i*(i+1)/2<n, 0,
`if`(n=0, 1, b(n, i-1, d+1)+`if`(i>n, 0, d*b(n-i, i-1, 1))))
end:
a:= n-> b(n, n-1, 1):
seq(a(n), n=1..50); # Alois P. Heinz, Jul 08 2016
MATHEMATICA
b[n_, i_, d_] := b[n, i, d] = If[i*(i+1)/2 < n, 0, If[n == 0, 1, b[n, i-1, d+1] + If[i > n, 0, d*b[n-i, i-1, 1]]]];
a[n_] := b[n, n-1, 1];
Table[a[n], {n, 1, 50}] (* Jean-François Alcover, Jul 28 2016, after Alois P. Heinz *)
CROSSREFS
Sequence in context: A022908 A256310 A026390 * A328670 A294745 A352234
KEYWORD
nonn,nice
AUTHOR
EXTENSIONS
Edited by N. J. A. Sloane, Jun 20 2015
Terms a(25) and beyond from Joerg Arndt, Apr 09 2016
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)