A090369 Smallest divisor of 2n that is > 2, or 0 if no such divisor exists.

0, 4, 3, 4, 5, 3, 7, 4, 3, 4, 11, 3, 13, 4, 3, 4, 17, 3, 19, 4, 3, 4, 23, 3, 5, 4, 3, 4, 29, 3, 31, 4, 3, 4, 5, 3, 37, 4, 3, 4, 41, 3, 43, 4, 3, 4, 47, 3, 7, 4, 3, 4, 53, 3, 5, 4, 3, 4, 59, 3, 61, 4, 3, 4, 5, 3, 67, 4, 3, 4, 71, 3, 73, 4, 3, 4, 7, 3, 79, 4, 3, 4, 83, 3, 5, 4, 3, 4, 89, 3, 7, 4, 3, 4, 5

Offset

1,2

Links

Remi Eismann, Table of n, a(n) for n = 1..10000

Maple

A090369 := proc(n) local lf, i ; lf := numtheory[divisors](2*n) ; for i from 1 to nops(lf) do if op(i, lf) > 2 then RETURN( op(i, lf) ) ; fi ; od ; RETURN(0) ; end : for n from 0 to 100 do printf("%d, ", A090369(n)) ; od ; # R. J. Mathar, Jun 02 2006

Mathematica

Join[{0}, Table[SelectFirst[Divisors[2n], #>2&], {n, 2, 120}]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 24 2017 *)

Crossrefs

Cf. A090368, A020639, A117078, A117563, A118534.

Sequence in context: A203144 A109382 A342843 * A260031 A132293 A205398

Adjacent sequences: A090366 A090367 A090368 * A090370 A090371 A090372

Keyword

nonn,easy

Author

Lekraj Beedassy, Nov 27 2003

Extensions

More terms from Ray Chandler, Dec 02 2003

Edited by N. J. A. Sloane at the suggestion of Rémi Eismann, Sep 15 2007

Status

approved