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A276269 a(n) = n + the largest (if n is even), or the smallest (if n is odd) prime factor of n if n > 1; and a(1)=1. 1
1, 4, 6, 6, 10, 9, 14, 10, 12, 15, 22, 15, 26, 21, 18, 18, 34, 21, 38, 25, 24, 33, 46, 27, 30, 39, 30, 35, 58, 35, 62, 34, 36, 51, 40, 39, 74, 57, 42, 45, 82, 49, 86, 55, 48, 69, 94, 51, 56, 55, 54, 65, 106, 57, 60, 63, 60, 87, 118, 65, 122, 93, 66, 66, 70, 77, 134 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This is the underlying sequence for sequence A256393.

a(n) is never prime, since for n>1 it is alternatively divisible by A006530(n) then by A020639(n). This explains the existence of the sequences noted [p] in A256393 comments. There are also such [c] sequences where c is composite like for instance for c=8.

LINKS

Table of n, a(n) for n=1..67.

PROG

(PARI) a(n) = if (n==1, 1, my(f = factor(n)); if (n % 2, n + f[1, 1], n + f[#f~, 1]));

CROSSREFS

Cf. A006530 (Gpf), A020639 (Lpf), A256393.

Sequence in context: A155750 A159475 A098350 * A163173 A058640 A075653

Adjacent sequences:  A276266 A276267 A276268 * A276270 A276271 A276272

KEYWORD

nonn

AUTHOR

Michel Marcus, Aug 26 2016

STATUS

approved

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Last modified August 23 22:45 EDT 2019. Contains 326254 sequences. (Running on oeis4.)