The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A284413 Exponent of 3 in 2^n + 1. 1
 1, 0, 2, 0, 1, 0, 1, 0, 3, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 4, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 3, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 3, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 5, 0, 1, 0, 1, 0, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Records: a(3^(n-1)) = n and a(k) < n for k < 3^(n-1). Multiplicative because A051064 is. - Andrew Howroyd, Jul 28 2018 LINKS Indranil Ghosh, Table of n, a(n) for n = 1..1000 FORMULA a(n) = A051064(n) if n is odd, 0 otherwise. EXAMPLE a(27) = 4 because 2^27 + 1 = 134217729 = 3^4 * 19 * 87211. MATHEMATICA Table[If[OddQ[n], IntegerExponent[3n, 3], 0], {n, 100}] (* Indranil Ghosh, Mar 27 2017 *) PROG (MAGMA) [IsEven(n) select 0 else Factorization(3*n)[1][2]: n in [1..87]]; (PARI) a(n) = if(n%2, if(n<1, 0, 1 + valuation(n, 3)), 0); \\ Indranil Ghosh, Mar 27 2017 CROSSREFS Cf. A168570 (exponent of 3 in 2^n - 1). Sequence in context: A067432 A192174 A262202 * A323879 A129308 A159200 Adjacent sequences:  A284410 A284411 A284412 * A284414 A284415 A284416 KEYWORD nonn,mult AUTHOR Jon E. Schoenfield, Mar 26 2017 STATUS approved

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

Last modified August 4 14:04 EDT 2020. Contains 336201 sequences. (Running on oeis4.)