A119792 -id:A119792

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A119791

a(1) = 1, a(n) = number of divisors of n*a(n-1).

+10
4

1, 2, 4, 5, 3, 6, 8, 7, 6, 12, 12, 15, 8, 10, 12, 14, 8, 15, 8, 12, 18, 18, 12, 18, 18, 18, 12, 20, 12, 24, 16, 10, 16, 12, 24, 24, 16, 12, 18, 30, 16, 24, 16, 14, 24, 20, 12, 21, 8, 15, 12, 20, 12, 20, 18, 30, 24, 20, 12, 30, 16, 12, 24, 20, 18, 24, 16, 14, 16, 24, 16, 24, 16, 12

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OFFSET

1,2

COMMENTS

a(n)=A000005(n*a(n-1)) for n>1, a(1)=1;

see A119792 and A119793 for record values and where they occur: A119792(n)=a(A119793(n)).

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

MATHEMATICA

Fold[Append[#1, DivisorSigma[0, #1[[-1]]*#2]] &, {1}, Range[2, 74]] (* Ivan Neretin, Sep 01 2016 *)

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, May 24 2006

STATUS

approved

A119793

Where record values of A119791 occur.

+10
2

1, 2, 3, 4, 6, 7, 10, 12, 21, 28, 30, 40, 77, 105, 175, 210, 400, 462, 495, 560, 990, 1275, 1540, 3213, 7140, 10626, 15400, 27456, 32725, 49896, 58905, 77616, 144144, 248976