A080214 Binomial(greatest prime factor of n, smallest prime factor of n).

1, 1, 1, 1, 1, 3, 1, 1, 1, 10, 1, 3, 1, 21, 10, 1, 1, 3, 1, 10, 35, 55, 1, 3, 1, 78, 1, 21, 1, 10, 1, 1, 165, 136, 21, 3, 1, 171, 286, 10, 1, 21, 1, 55, 10, 253, 1, 3, 1, 10, 680, 78, 1, 3, 462, 21, 969, 406, 1, 10, 1, 465, 35, 1, 1287, 55, 1, 136, 1771, 21, 1, 3, 1, 666, 10

Offset

1,6

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Mathematica

a[n_] := With[{f = FactorInteger[n]}, Binomial[f[[-1, 1]], f[[1, 1]]]];
Array[a, 100] (* Jean-François Alcover, Dec 02 2021 *)

Prog

(PARI) A080214(n) = if(1==n, n, my(f = factor(n), lpf = f[1, 1], gpf = f[#f~, 1]); binomial(gpf, lpf)); \\ Antti Karttunen, Sep 06 2018

Crossrefs

Cf. A006530, A020639, A080215, A080211.

Sequence in context: A340149 A340075 A307847 * A263383 A185620 A096066

Adjacent sequences: A080211 A080212 A080213 * A080215 A080216 A080217

Keyword

nonn,look

Author

Reinhard Zumkeller, Feb 06 2003

Status

approved