

A129643


a(1)=1. a(n) = a(n1)*(b(n1)+1), where {b(k)} is the concatenated list of the positive divisors of the terms of {a(k)}.


2



1, 2, 4, 12, 24, 72, 360, 720, 2160, 8640, 43200, 302400, 3931200, 7862400, 23587200, 94348800, 471744000, 3302208000, 29719872000, 386358336000, 9658958400000, 19317916800000, 57953750400000, 231815001600000, 1159075008000000, 8113525056000000, 73021725504000000
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..27.


EXAMPLE

The list of positive divisors of the terms of {a(k)} is (sequence A129644) 1;1,2;1,2,4;1,2,3,4,6,12;.... The nth term of {a(k)} is product{k=1 to n1}(A129644(k)+1).


MAPLE

A129643 := proc(nmax) local a, b, n, a_1; a := [1] ; b := [1] ; while nops(a) < nmax do n := nops(a)+1 ; a_1 := op(1, a) ; a := [op(a), a_1*(op(n1, b)+1)] ; a_1 := op(1, a) ; if nops(b) < nmax then b := [op(b), op(numtheory[divisors](a_1))] ; fi ; od: RETURN(a) ; end: A129643(40) ; # R. J. Mathar, Oct 16 2007


CROSSREFS

Cf. A129644.
Sequence in context: A135139 A161894 A062177 * A200337 A320931 A096421
Adjacent sequences: A129640 A129641 A129642 * A129644 A129645 A129646


KEYWORD

nonn,base


AUTHOR

Leroy Quet, Apr 25 2007


EXTENSIONS

More terms from R. J. Mathar, Oct 16 2007
Corrected by N. J. A. Sloane, Nov 04 2007


STATUS

approved



