A002221 a(n) is the number of partitions of 4n that can be obtained by adding together four (not necessarily distinct) partitions of n. (Formerly M3861 N1583)

1, 5, 15, 55, 140, 448, 1022, 2710, 6048, 14114, 28831, 64091, 123649, 251295, 476835, 916972, 1654044, 3080159, 5377431, 9624588, 16490017, 28433473, 47423409, 80279375

Offset

1,2

References

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).

Links

Table of n, a(n) for n=1..24.

N. Metropolis and P. R. Stein, An elementary solution to a problem in restricted partitions, J. Combin. Theory, 9 (1970), 365-376.

Crossrefs

See A002219 for further details. Cf. A002220, A002222, A213074.

A column of A213086.

Sequence in context: A147324 A109245 A243076 * A007714 A123011 A006358

Adjacent sequences: A002218 A002219 A002220 * A002222 A002223 A002224

Keyword

nonn,more

Author

N. J. A. Sloane

Extensions

Edited by N. J. A. Sloane, Jun 03 2012

a(12)-a(16) from Alois P. Heinz, Jul 10 2012

a(17)-a(24) from Sean A. Irvine, Sep 05 2013

Status

approved