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A046353 Odd composite numbers whose sum of prime factors is palindromic (counted with multiplicity). 3
9, 15, 27, 45, 57, 85, 121, 123, 259, 305, 351, 403, 413, 415, 483, 495, 575, 597, 627, 639, 663, 687, 689, 705, 717, 735, 807, 875, 893, 931, 935, 985, 989, 1073, 1135, 1183, 1203, 1207, 1263, 1285, 1293, 1331, 1353, 1383, 1385, 1407, 1473, 1505, 1545 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

John Cerkan, Table of n, a(n) for n = 1..10000

EXAMPLE

689 = 13 * 53 -> 13 + 53 = 66 and 66 is a palindrome.

MATHEMATICA

palQ[n_]:=Reverse[x=IntegerDigits[n]]==x; Select[Range[9, 1545, 2], !PrimeQ[#]&&palQ[Total[Times@@@FactorInteger[#]]]&] (* Jayanta Basu, Jun 05 2013 *)

PROG

(Python)

from sympy import factorint

def is_046353(n):

    if n % 2 == 0: return False

    f = factorint(n)

    if sum([f[i] for i in f]) < 2: return False

    sfa = sum([i*f[i] for i in f])

    if sfa == int(str(sfa)[::-1]): return True

    return False # John Cerkan, Apr 24 2018

CROSSREFS

Cf. A046352, A046354.

Sequence in context: A129401 A164385 A258813 * A046356 A248381 A060874

Adjacent sequences:  A046350 A046351 A046352 * A046354 A046355 A046356

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Jun 15 1998

EXTENSIONS

Name clarified and offset changed by John Cerkan, Apr 24 2018

STATUS

approved

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Last modified November 15 03:35 EST 2018. Contains 317224 sequences. (Running on oeis4.)