A092873 Prime factors of the odd terms of A007755.

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

Offset: 1

Author

T. D. Noe, Mar 08 2004

Keywords

• nonn

Comments

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.

Links

• T. D. Noe, Table of n, a(n) for n=1..288 (odd primes in the first 1000 terms of A007755)
• P. A. Catlin, Concerning the iterated phi-function, Amer Math. Monthly 77 (1970), pp. 60-61.

Extensions

More terms from T. D. Noe, Aug 03 2005

a(21) corrected and comment deleted by T. D. Noe, Nov 18 2008