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 A244397 Consider a number n with m decimal digits, m>1. The sequence lists the numbers n such that the prefix of length m-1 and the suffix of length m-1 have both the same distinct prime divisors. 0
 22, 24, 28, 33, 39, 42, 44, 48, 55, 66, 77, 82, 84, 88, 93, 99, 111, 124, 164, 222, 248, 333, 444, 526, 548, 555, 666, 724, 777, 842, 888, 999, 1111, 1248, 1664, 2162, 2222, 2500, 2855, 3200, 3333, 3600, 3748, 4324, 4444, 4864, 5042, 5128, 5555, 5768, 5882 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Let x(0)x(1)...x(q-1)x(q) denote the decimal expansion of a number n. The sequence lists the numbers n such that the prefix p = x(0)x(1)...x(q-1) and the suffix x(1)...x(q-1)x(q) have the same prime distinct divisors. LINKS Table of n, a(n) for n=1..51. EXAMPLE 3748 is in the sequence because 374 and 748 have the same prime divisors: {2,11,17). MAPLE with(numtheory): for n from 10 to 10000 do: x:=convert(n, base, 10):n1:=nops(x): s1 := n mod 10^ilog10(n): s2:=(n-irem(n, 10))/10: x1:=factorset(s1):x2:=factorset(s2): if x1 = x2 and x1 <>{} then printf(`%d, `, n): else fi: od: CROSSREFS Cf. A244394. Sequence in context: A067189 A030593 A235807 * A138603 A181454 A155911 Adjacent sequences: A244394 A244395 A244396 * A244398 A244399 A244400 KEYWORD nonn,base AUTHOR Michel Lagneau, Jun 27 2014 STATUS approved

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Last modified September 8 19:48 EDT 2024. Contains 375759 sequences. (Running on oeis4.)