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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A256415 Positive integers with primes p replaced by 2p and also 3p replaced by 2p. 4
1, 4, 6, 4, 10, 4, 14, 8, 6, 10, 22, 12, 26, 14, 10, 16, 34, 18, 38, 20, 14, 22, 46, 24, 25, 26, 27, 28, 58, 30, 62, 32, 22, 34, 35, 36, 74, 38, 26, 40, 82, 42, 86, 44, 45, 46, 94, 48, 49, 50, 34, 52, 106, 54, 55, 56, 38, 58, 118, 60, 122, 62, 63, 64, 65, 66, 134, 68, 46, 70 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The smoothed version of A064413 (A256417) is a rearrangement of these terms.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

MAPLE

# Apply p->2p, 3p->2p to a sequence t1

SMOOTH:=proc(t1) local M, t2, n; t2:=[]: M:=nops(t1):

for n from 1 to M do

if isprime(t1[n]) then t2:=[op(t2), 2*t1[n]];

elif (t1[n] mod 3 = 0 ) and isprime(t1[n]/3) then t2:=[op(t2), 2*t1[n]/3];

else t2:=[op(t2), t1[n]]; fi; od: t2; end;

SMOOTH([seq(n, n=1..200)]);

MATHEMATICA

Range[70] /. {n_ /; PrimeQ[n] -> 2n, n_ /; PrimeQ[n/3] -> 2n/3} (* Jean-Fran├žois Alcover, Aug 04 2018 *)

Table[Which[PrimeQ[n], 2n, PrimeQ[n/3], 2 n/3, True, n], {n, 120}] (* Harvey P. Dale, Jun 08 2019 *)

PROG

(Haskell)

a256415 n | a010051 n == 1 = 2 * n

          | r == 0 && a010051 n' == 1 = 2 * n'

          | otherwise = n

          where (n', r) = divMod n 3

-- Reinhard Zumkeller, Apr 05 2015

CROSSREFS

Cf. A010051, A064413, A256416 (the sorted sequence), A256417.

Sequence in context: A088740 A088738 A114595 * A143545 A328045 A277278

Adjacent sequences:  A256412 A256413 A256414 * A256416 A256417 A256418

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Apr 05 2015

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 6 22:23 EDT 2020. Contains 333291 sequences. (Running on oeis4.)