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A002270 Composite n such that n*sigma(n) == 2 (mod phi(n)). 1
4, 6, 22 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

REFERENCES

M. V. Subbarao, On two congruences for primality. Pacific J. Math. 52 (1974), 261-268.

J. Roberts, Lure of the Integers, Math. Assoc. America, 1992, p. 147.

CROSSREFS

Cf. A051948.

Sequence in context: A019147 A026722 A151520 * A088228 A108636 A101143

Adjacent sequences:  A002267 A002268 A002269 * A002271 A002272 A002273

KEYWORD

nonn,fini,full,bref

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

EXTENSIONS

Definition corrected by Tanya Khovanova, Nov 05 2007

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Last modified February 17 07:41 EST 2012. Contains 205998 sequences.