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A144585 Composites whose sum of prime factors is an odd nonprime (counted with multiplicity). 0
14, 20, 24, 26, 27, 38, 44, 46, 62, 68, 74, 86, 92, 94, 105, 106, 112, 116, 122, 124, 125, 126, 134, 146, 150, 152, 158, 160, 164, 166, 171, 178, 180, 188, 192, 194, 195, 206, 208, 212, 216, 218, 226, 231, 232, 234, 236, 243, 244, 254, 255, 261, 262, 272, 275 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

14 is a term because 14 = 2*7 and 2+7 = 9 (an odd nonprime);

20 is a term because 20 = 2*2*5 and 2+2+5 = 9,

24 is a term because 24 = 2*2*2*3 and 2+2+2+3 = 9;

26 is a term because 26 = 2*13 and 2+13 = 15 (also an odd nonprime).

MAPLE

ifac := proc (n) local L, x: L := ifactors(n)[2]: map(proc (x) options operator, arrow: seq(x[1], j = 1 .. x[2]) end proc, L) end proc: a := proc (n) local b: b := add(ifac(n)[j], j = 1 .. nops(ifac(n))): if isprime(n) = false and `mod`(b, 2) = 1 and isprime(b) = false then n else end if end proc: seq(a(n), n = 1 .. 280); # Emeric Deutsch, Jan 27 2009

CROSSREFS

Cf. A002808, A036349, A046363, A141468.

Sequence in context: A074851 A193672 A087678 * A186193 A285426 A108874

Adjacent sequences:  A144582 A144583 A144584 * A144586 A144587 A144588

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Jan 04 2009

EXTENSIONS

Corrected (removed 81; added 126, 158) and extended by Emeric Deutsch, Jan 27 2009

Example section edited by Jon E. Schoenfield, Jan 15 2019

STATUS

approved

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Last modified August 3 03:52 EDT 2021. Contains 346435 sequences. (Running on oeis4.)