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A033620 Numbers all of whose prime factors are palindromes. 7
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 27, 28, 30, 32, 33, 35, 36, 40, 42, 44, 45, 48, 49, 50, 54, 55, 56, 60, 63, 64, 66, 70, 72, 75, 77, 80, 81, 84, 88, 90, 96, 98, 99, 100, 101, 105, 108, 110, 112, 120, 121, 125, 126, 128, 131 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

Multiplicative closure of A002385; A051038 and A046368 are subsequences. [Reinhard Zumkeller, Apr 11 2011]

PROG

(Haskell)

a033620 n = a033620_list !! (n-1)

a033620_list = filter chi [1..] where

   chi n = a136522 spf == 1 && (n' == 1 || chi n') where

      n' = n `div` spf

      spf = a020639 n  -- cf. A020639

-- Reinhard Zumkeller, Apr 11 2011

CROSSREFS

Sequence in context: A147820 A194424 A033892 * A033637 A084347 A051038

Adjacent sequences:  A033617 A033618 A033619 * A033621 A033622 A033623

KEYWORD

nonn,base,easy

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified February 13 06:35 EST 2012. Contains 205451 sequences.