A116965 Integers that can be expressed as the sum of 2 double factorials.

2, 3, 4, 5, 6, 9, 10, 11, 16, 17, 18, 23, 30, 49, 50, 51, 56, 63, 96, 106, 107, 108, 113, 120, 153, 210, 385, 386, 387, 392, 399, 432, 489, 768, 946, 947, 948, 953, 960, 993, 1050, 1329, 1890, 3841, 3842, 3843, 3848, 3855, 3888, 3945, 4224, 4785, 7680, 10396

Offset

1,1

Links

Table of n, a(n) for n=1..54.

Example

16 = 0!! + 5!! = 1!! + 5!!.
113 = 4!! + 7!!

Mathematica

Take[Union@Flatten@Table[i!! + j!!, {i, 13}, {j, 0, i}], 56] (* Robert G. Wilson v *)

Crossrefs

Cf. A111222.

Sequence in context: A032975 A119356 A137582 * A356007 A306975 A123054

Adjacent sequences: A116962 A116963 A116964 * A116966 A116967 A116968

Keyword

easy,nonn

Author

Paolo P. Lava and Giorgio Balzarotti, Mar 31 2006

Extensions

More terms from Robert G. Wilson v, Apr 01 2006

Status

approved