A115650 Triangular numbers which are the sum of distinct double factorials (A006882).

1, 3, 6, 10, 15, 21, 28, 66, 105, 120, 153, 171, 435, 561, 946, 1378, 1485, 3916, 4005, 4278, 4851, 4950, 11781, 14365, 15576, 47586, 50086, 51360, 57970, 60378, 60726, 61425, 61776, 139128, 145530, 146070, 149878, 150426, 182710, 659526, 702705

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..41.

Example

T(527) = 19128 = 13!! + 10!! + 7!! + 6!!.

Crossrefs

Cf. A006882, A115648, A115649.

Sequence in context: A117520 A147846 A062099 * A025745 A175724 A335184

Adjacent sequences: A115647 A115648 A115649 * A115651 A115652 A115653

Keyword

nonn

Author

Giovanni Resta, Jan 28 2006

Status

approved