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A015721 Composite and even n such that phi(n) * sigma(n) is one less than a square. +0
1
6, 22, 44, 76, 82, 140, 190, 354, 392, 650, 944, 1072, 1142, 1150, 1668, 2276, 4176, 4192, 4262, 5090, 7260, 8660, 15026, 16064, 22926, 29746, 39436, 42872, 74666, 87498, 94786, 101882, 115772, 118928, 127580, 151348 (list; graph; listen)
OFFSET

0,1
REFERENCES

R. K. Guy, Divisors and desires, Amer. Math. Monthly, 104 (1997), 359-360.

CROSSREFS

Sequence in context: A056821 A031083 A031305 this_sequence A072972 A092185 A034134

Adjacent sequences: A015718 A015719 A015720 this_sequence A015722 A015723 A015724

KEYWORD

nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com)

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Last modified November 30 22:12 EST 2008. Contains 150989 sequences.

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