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A015713 phi(n) * sigma(n) + k^2 is not a square for any k. +0
1
4, 9, 18, 49, 81, 98, 121, 162, 242, 361, 529, 722, 729, 961, 1058, 1458, 1849, 1922, 2209, 2401, 3481, 3698, 4418, 4489, 4802, 5041, 6241, 6561, 6889, 6962, 8978, 10082, 10609, 11449, 12482, 13122, 13778, 14641, 16129, 17161 (list; graph; listen)
OFFSET

0,1
REFERENCES

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

CROSSREFS

Sequence in context: A122039 A083706 A074896 this_sequence A049198 A146303 A147977

Adjacent sequences: A015710 A015711 A015712 this_sequence A015714 A015715 A015716

KEYWORD

nonn

AUTHOR

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

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Last modified December 17 23:40 EST 2009. Contains 171025 sequences.

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