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 A105432 Numbers n such that the near-repdigit number consisting of n-1 1's followed by a terminal 3 (i.e., of the form 111...1113) is composite. 1
 4, 6, 7, 8, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Complement of A097683. Numbers k such that (10^n + 17)/9 is composite (see A098406). LINKS PROG (PARI) isok(n) = ! isprime((10^n + 17)/9); \\ Michel Marcus, Jul 27 2017 CROSSREFS Cf. A098406, A105433. Sequence in context: A225551 A247359 A305415 * A324704 A203168 A284820 Adjacent sequences:  A105429 A105430 A105431 * A105433 A105434 A105435 KEYWORD nonn,base AUTHOR Lekraj Beedassy, Apr 08 2005 STATUS approved

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Last modified September 19 18:06 EDT 2020. Contains 337181 sequences. (Running on oeis4.)