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A067577 a(n) = Product_{i=1..n} sigma(i) * Sum_{i=1..n} 1/sigma(i). 0
1, 4, 19, 145, 954, 11952, 101664, 1573344, 21179232, 390661056, 4857760512, 138055228416, 1989835352064, 48554918608896, 1184490930438144, 37179368055373824, 683493250562260992, 26913000032107757568, 548273767789158727680, 23227773590084738088960, 751700319286194622955520 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..21.

PROG

(PARI) a(n) = prod(i=1, n, sigma(i)) * sum(i=1, n, 1/sigma(i)); \\ Michel Marcus, Jan 09 2021

CROSSREFS

Cf. A000230 (sigma), A066780, A212717, A212718.

Sequence in context: A208992 A321388 A212717 * A225904 A203010 A249785

Adjacent sequences:  A067574 A067575 A067576 * A067578 A067579 A067580

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Jan 30 2002

EXTENSIONS

More terms from Michel Marcus, Jan 09 2021

STATUS

approved

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Last modified April 11 02:02 EDT 2021. Contains 342886 sequences. (Running on oeis4.)