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A180708 a(n) = sigma(3*a(n-1)) for n>1 with a(1)=1. 0
1, 4, 28, 224, 2016, 20160, 243840, 2545920, 30905280, 388908036, 3622707200, 44117911764, 387754160640, 5065246517760, 67333642371072, 829993839244416, 9887956143636480, 150394118343146496, 1797812804753817600 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..19.

PROG

(PARI) a(n)=if(n==1, 1, sigma(3*a(n-1)))

CROSSREFS

Cf. A180707.

Sequence in context: A005810 A121203 A192620 * A191094 A220876 A152599

Adjacent sequences:  A180705 A180706 A180707 * A180709 A180710 A180711

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Sep 18 2010

STATUS

approved

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Last modified May 6 22:59 EDT 2021. Contains 343599 sequences. (Running on oeis4.)