A120374 Median of prime divisors of 2n+1 (with multiplicity).

3, 5, 7, 3, 11, 13, 4, 17, 19, 5, 23, 5, 3, 29, 31, 7, 6, 37, 8, 41, 43, 3, 47, 7, 10, 53, 8, 11, 59, 61, 3, 9, 67, 13, 71, 73, 5, 9, 79, 3, 83, 11, 16, 89, 10, 17, 12, 97, 3, 101, 103, 5, 107, 109, 20, 113, 14, 3, 12, 11, 22, 5, 127, 23, 131, 13, 3, 137, 139, 25, 12, 17, 7, 149, 151

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

165 = 3*5*11, an odd number of prime divisors; the middle one is 5, so a(165) = 5. 315 = 3*3*5*7, an even number of prime divisors; the middle two are 3 and 5; their mean is 4, so a(315) = 4.

Mathematica

mpd[n_]:=Median[Flatten[Table[#[[1]], #[[2]]]&/@FactorInteger[n]]]; Table[ mpd[ n], {n, 3, 201, 2}] (* Harvey P. Dale, Dec 03 2021 *)

Crossrefs

Cf. A088836 (first difference at 2n+1 = 45).

Sequence in context: A051417 A326577 A090368 * A088836 A076565 A286517

Adjacent sequences: A120371 A120372 A120373 * A120375 A120376 A120377

Keyword

nonn

Author

Franklin T. Adams-Watters, Jun 27 2006

Status

approved