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A069520 (1/n)*sum(d|n,d*sigma(d)) is an integer. 2
1, 39, 793, 1638, 2379, 2394, 7137, 8190, 11970, 14274, 18135, 19530, 30927, 31122, 35685, 36270, 50700, 61854, 71370, 76921, 81900, 92781, 99918, 119700, 154635, 155610, 185562, 195300, 230763, 253890, 269500, 299754, 304038, 309270 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Sequence A232354 starts in a very similar way, and the two sequences have a common subsequence A232067 = (1, 39, 793, 2379, 7137, 76921, 230763, ...), but neither is a subsequence of the other. - M. F. Hasler, Nov 24 2013

LINKS

Table of n, a(n) for n=1..34.

PROG

(PARI) is_A069520(n)=!(sumdiv(n, d, d*sigma(d))%n) \\ - M. F. Hasler, Nov 24 2013

CROSSREFS

Sequence in context: A010991 A221358 A194133 * A232354 A232067 A247222

Adjacent sequences:  A069517 A069518 A069519 * A069521 A069522 A069523

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Apr 16 2002

STATUS

approved

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Last modified September 16 23:53 EDT 2021. Contains 347477 sequences. (Running on oeis4.)