The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A219037 Numbers k such that k divides 2^k + 2 and (k-1) divides 2^k + 1. 3
 2, 6, 66, 73786976294838206466 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Also, numbers k such that 2^k == k-2 (mod k*(k-1)). The sequence is infinite: if m is in this sequence, then so is 2^m + 2. No other terms below 10^20. REFERENCES W. Sierpinski, 250 Problems in Elementary Number Theory. New York: American Elsevier, 1970. Problem #18. LINKS Kin Y. Li et al., Solution to Problem 323, Mathematical Excalibur 14(2), 2009, p. 3. FORMULA Conjecture: a(n+1) = 2^a(n) + 2 for all n. CROSSREFS Intersection of A006517 and A055685. Cf. A217468, A216822, A171959. Sequence in context: A167006 A087331 A097419 * A156458 A244494 A136268 Adjacent sequences: A219034 A219035 A219036 * A219038 A219039 A219040 KEYWORD nonn,hard,more AUTHOR Max Alekseyev, Nov 10 2012 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 28 19:22 EDT 2023. Contains 361596 sequences. (Running on oeis4.)