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 A246569 Semiprimes with strictly increasing product of digits. 4
 4, 6, 9, 25, 26, 35, 38, 39, 49, 58, 69, 87, 249, 259, 278, 289, 299, 398, 478, 489, 579, 589, 679, 689, 699, 789, 799, 889, 899, 2589, 2599, 2779, 2798, 2899, 3799, 3898, 3899, 4798, 4979, 4989, 5799, 5899, 5999, 6989, 6999, 7899, 7999, 8899, 9899, 19999, 26799 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Primes of this form are at A230041. LINKS K. D. Bajpai, Table of n, a(n) for n = 1..169 EXAMPLE a(6) = 35 = 5 * 7, which is semiprime. Product of its digits = 3 * 5 = 15. a(7) = 38 = 2 * 19, which is semiprime. Product of its digits = 3 * 8 = 24. Since 24 > 15, 35 and 38 appear in the sequence. MATHEMATICA A246569 = { }; t = 0; Do[s = Apply[Times, IntegerDigits[k]]; If[PrimeOmega[k] == 2 && s > t, t = s; AppendTo[A246569, k]], {k, 1, 30000}]; A246569 CROSSREFS Cf. A001358, A230041. Sequence in context: A229129 A272436 A338309 * A368648 A326063 A085721 Adjacent sequences: A246566 A246567 A246568 * A246570 A246571 A246572 KEYWORD nonn,base AUTHOR K. D. Bajpai, Aug 30 2014 STATUS approved

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Last modified September 11 08:42 EDT 2024. Contains 375814 sequences. (Running on oeis4.)