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 A256673 Odd numbers with prime arithmetic derivative A003415. 2
 105, 165, 231, 255, 273, 285, 345, 357, 385, 399, 455, 465, 483, 555, 561, 595, 609, 645, 651, 663, 665, 715, 795, 805, 861, 885, 915, 957, 969, 987, 1001, 1015, 1023, 1045, 1095, 1131, 1185, 1281, 1295, 1309, 1311, 1335, 1353, 1407, 1443, 1463, 1479, 1495, 1515, 1533, 1545, 1547, 1551, 1615, 1635, 1645 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The subsequence of odd numbers in A157037. In order to have a prime arithmetic derivative (satisfying (mn)' = m'n + m n', p' = 1 for primes), an odd number must have at least 3 distinct prime factors. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 EXAMPLE a(1)=105 is the smallest odd number with prime arithmetic derivative A003415(3*5*7) = 5*7 + 3*7 + 3*5 = 71. PROG (Haskell) a256673 n = a256673_list !! (n-1) a256673_list = filter odd a157037_list -- Reinhard Zumkeller, Apr 08 2015 CROSSREFS Cf. A003415, A157037. Sequence in context: A036798 A119434 A091495 * A046405 A128278 A234103 Adjacent sequences:  A256670 A256671 A256672 * A256674 A256675 A256676 KEYWORD nonn AUTHOR M. F. Hasler, Apr 07 2015 STATUS approved

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Last modified May 24 06:53 EDT 2019. Contains 323529 sequences. (Running on oeis4.)