A002220 a(n) is the number of partitions of 3n that can be obtained by adding together three (not necessarily distinct) partitions of n. (Formerly M3395 N1374)

1, 4, 10, 30, 65, 173, 343, 778, 1518, 3088, 5609, 10959, 18990, 34441, 58903, 102044, 167499, 282519, 451529, 737208, 1160102, 1836910, 2828466, 4410990, 6670202, 10161240, 15186315, 22758131, 33480869

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..29.

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. A002221, A002222, A213074.

A column of A213086.

Sequence in context: A330529 A048044 A047188 * A222807 A090578 A007713

Adjacent sequences: A002217 A002218 A002219 * A002221 A002222 A002223

Keyword

nonn

Author

N. J. A. Sloane

Extensions

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

a(12)-a(20) from Alois P. Heinz, Jul 10 2012

a(21)-a(29) from Sean A. Irvine, Sep 05 2013

Status

approved