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A092873 Prime factors of the odd terms of A007755. +0
3
3, 5, 11, 17, 41, 83, 137, 257, 641, 1097, 17477, 65537, 140417, 557057, 2384897, 4227137, 35946497, 71304257, 541073537, 2281701377, 2336497860617, 600470787982337, 2278291849363457, 4538923050090497, 38280596832649217 (list; graph; listen)
OFFSET

1,1

COMMENT

Catlin shows that if A007755(n) is odd and composite, then its factors are among the A007755(k), k < n. Note that the five Fermat primes are in this sequence.

REFERENCES

P. A. Catlin, Concerning the iterated phi function, Amer. Math. Monthly, Vol. 77, No. 1 (1970), 60-61.

LINKS

T. D. Noe, Table of n, a(n) for n=1..288 (odd primes in the first 1000 terms of A007755)

CROSSREFS

Sequence in context: A096479 A129809 A040176 this_sequence A158641 A019386 A154622

Adjacent sequences: A092870 A092871 A092872 this_sequence A092874 A092875 A092876

KEYWORD

nonn

AUTHOR

T. D. Noe (noe(AT)sspectra.com), Mar 08 2004

EXTENSIONS

More terms from T. D. Noe (noe(AT)sspectra.com), Aug 03 2005

a(21) corrected and comment deleted. - T. D. Noe (noe(AT)sspectra.com), Nov 18 2008

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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