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A141293 Prime factors of numbers of the form x^2 + 1 which themselves are not of this form. 1
13, 29, 41, 53, 61, 73, 89, 97, 109, 113, 137, 149, 157, 173, 181, 193, 229, 233, 241, 269, 277, 281, 293, 313, 317, 337, 349, 353, 373, 389, 397, 409, 421, 433, 449, 457, 461, 509, 521, 541, 557, 569, 593, 601, 613, 617, 641, 653, 661, 673, 701, 709, 733, 757, 761, 769 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Equivalently, primes p == 1 mod 4 which are not of the form k^2 + 1.

Same as A002144 with A002496 removed.

REFERENCES

A. K. Devaraj, "Euler's Generalization of Fermat's Theorem-A Further Generalization", in ISSN #1550-3747, Proceedings of Hawaii Intl Conference on Statistics, Mathematics & Related Fields, 2004.

MATHEMATICA

Complement[Select[4*Range[400]+1, PrimeQ], Select[Range[40]^2+1, PrimeQ]] - T. D. Noe (noe(AT)sspectra.com), Jun 27 2008

CROSSREFS

Cf. A002144, A002145, A002496.

Sequence in context: A141555 A036974 A045472 * A120827 A044074 A044455

Adjacent sequences:  A141290 A141291 A141292 * A141294 A141295 A141296

KEYWORD

nonn

AUTHOR

A. K. Devaraj (dkandadai(AT)gmail.com), Jun 23 2008

EXTENSIONS

Corrected and extended by T. D. Noe and N. J. A. Sloane (njas(AT)research.att.com), Jun 27 2008

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Last modified February 17 14:19 EST 2012. Contains 206038 sequences.