A115648 Square numbers which are the sum of distinct double factorials (A006882).

1, 4, 9, 16, 25, 49, 64, 121, 169, 400, 441, 961, 1444, 3844, 3969, 4225, 4356, 4900, 5184, 10404, 11449, 11881, 14400, 15625, 47089, 47524, 56644, 57600, 139129, 145924, 149769, 182329, 192721, 695556, 705600, 792100, 837225, 2073600

Offset

1,2

Comments

Double factorials 0!! and 1!! are not considered distinct. Note that double factorial (n!!) is different from (n!)!.

Links

Table of n, a(n) for n=1..38.

Example

10404 = 102^2 = 1!! + 4!! + 11!!.

Crossrefs

Cf. A006882, A115649, A115650, A115651, A025494.

Sequence in context: A063735 A056798 A036454 * A082522 A279096 A299153

Adjacent sequences: A115645 A115646 A115647 * A115649 A115650 A115651

Keyword

nonn

Author

Giovanni Resta, Jan 28 2006

Status

approved