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 A138510 Smallest number b such that in base b representation the prime factors of the n-th semiprime (A001358) have equal lengths. 4
 1, 2, 1, 6, 8, 3, 3, 12, 1, 14, 12, 18, 2, 20, 14, 24, 1, 18, 4, 20, 30, 32, 4, 24, 38, 4, 42, 5, 44, 30, 4, 32, 48, 5, 54, 38, 5, 60, 5, 1, 62, 42, 44, 5, 68, 48, 72, 2, 30, 74, 32, 80, 54, 5, 84, 1, 60, 90, 62, 38, 3, 98, 68, 102, 6, 42, 104, 3, 72, 108, 44, 6, 110, 74, 3, 114, 48, 80 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = 1 iff A001358(n) is a prime square (A001248); a(A138511(n)) = A084127(A138511(n)) + 1. LINKS EXAMPLE n=91=7*13: 7 = '111'[binary] = '21'[ternary] = '13'[base4] and 13 = '1101'[binary] = '111'[ternary] = '31'[base4], therefore 91 is a term, a(31) = 91. CROSSREFS Cf. A078972, A085721. Sequence in context: A136470 A220884 A217877 * A026215 A026220 A138750 Adjacent sequences:  A138507 A138508 A138509 * A138511 A138512 A138513 KEYWORD nonn,base AUTHOR Reinhard Zumkeller, Mar 21 2008 STATUS approved

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Last modified May 25 12:28 EDT 2013. Contains 225647 sequences.