A037279 If n is composite, replace n with the concatenation of its nontrivial divisors, otherwise a(n) = n.

1, 2, 3, 2, 5, 23, 7, 24, 3, 25, 11, 2346, 13, 27, 35, 248, 17, 2369, 19, 24510, 37, 211, 23, 2346812, 5, 213, 39, 24714, 29, 23561015, 31, 24816, 311, 217, 57, 234691218, 37, 219, 313, 24581020, 41, 23671421, 43, 241122, 35915, 223, 47, 23468121624, 7

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• base

Examples

			Divisors of 12 are 1,2,3,4,6,12, so a(12)=2346.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A037278, A120712, A106708.

Programs

Maple

A037279 := proc(n) local dvs ; if isprime(n) or n = 1 then n; else dvs := [op(numtheory[divisors](n) minus {1,n} )] ; dvs := sort(dvs) ; cat(op(dvs)) ; fi ; end: seq(A037279(n),n=1..80) ; # R. J. Mathar, Jul 23 2007

Mathematica

f[n_]:=If[PrimeQ[n],n,FromDigits[Flatten[IntegerDigits/@Rest[ Most[ Divisors[n]]]]]]; Join[{1},Array[f,50,2]] (* Harvey P. Dale, Sep 24 2012 *)

Extensions

More terms from Erich Friedman

Edited by N. J. A. Sloane, Aug 29 2008 at the suggestion of R. J. Mathar