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

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

Author

N. J. A. Sloane

Keywords

• nonn
• more

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

• 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.

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