A242342 a(n) = binomial(n, smallest non-divisor of n).

0, 0, 3, 4, 10, 15, 21, 56, 36, 120, 55, 792, 78, 364, 105, 560, 136, 3060, 171, 1140, 210, 1540, 253, 42504, 300, 2600, 351, 3276, 406, 27405, 465, 4960, 528, 5984, 595, 376992, 666, 8436, 741, 9880, 820, 111930, 903, 13244, 990, 15180, 1081, 1712304, 1176

Offset

1,3

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Formula

a(n) = A007318(n, A007978(n)) for n > 2.

a(2*n-1) = A014105(n).

Mathematica

Join[{0, 0}, Table[Binomial[n, Complement[Range[DivisorSigma[0, n]], Divisors[ n]][[1]]], {n, 3, 50}]] (* Harvey P. Dale, May 23 2019 *)

Prog

(Haskell)
a242342 n = if n <= 2 then 0 else a007318' n (a007978 n)

Crossrefs

Cf. A014105.

Sequence in context: A319719 A347568 A048155 * A204292 A218277 A103080

Adjacent sequences: A242339 A242340 A242341 * A242343 A242344 A242345

Keyword

nonn

Author

Reinhard Zumkeller, May 11 2014

Status

approved