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 A173101 Self-describing semiprimes. 1
 22, 10183133, 10183331, 10213223 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This is to A001358 as A108810 is to A000040. LINKS FORMULA {A109776 INTERSECTION A001358}. a(n) = n-th integer k such that OMEGA(k)=2 where OMEGA(n) is the sum of the exponents in the prime decomposition of k, and reading the number (in base 10) in successive pairs of digits gives a (possibly redundant) description of the number. EXAMPLE a(1) = 22 because "22" does indeed consist of "two 2's" and 22 = 2 * 11 is semiprime. a(4) = 10213223 because 10213223 consists of one "0", two 1's, three 2's, and two 3's; and 10213223 = 41 * 249103 is semiprime. CROSSREFS Cf. A001358, A108810, A109776. Sequence in context: A267492 A013816 A104789 * A047841 A267498 A267497 Adjacent sequences:  A173098 A173099 A173100 * A173102 A173103 A173104 KEYWORD base,more,nonn AUTHOR Jonathan Vos Post, Feb 09 2010 STATUS approved

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Last modified January 16 19:49 EST 2019. Contains 319206 sequences. (Running on oeis4.)