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 A102415 Greatest semiprime less than n-th prime. 5
 4, 6, 10, 10, 15, 15, 22, 26, 26, 35, 39, 39, 46, 51, 58, 58, 65, 69, 69, 77, 82, 87, 95, 95, 95, 106, 106, 111, 123, 129, 134, 134, 146, 146, 155, 161, 166, 169, 178, 178, 187, 187, 194, 194, 209, 221, 226, 226, 226, 237, 237, 249, 254, 262, 267, 267, 274, 278, 278 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,1 LINKS Amiram Eldar, Table of n, a(n) for n = 3..10000 Eric Weisstein's World of Mathematics, Semiprime FORMULA a(n) < A000040(n) < A102414(n). EXAMPLE a(3) = 4 since 4 is the greatest semiprime less than prime(3) = 5. MATHEMATICA a[n_] := Module[{m = Prime[n] - 1}, While[PrimeOmega[m] != 2, m--]; m]; Array[a, 60, 3] (* Amiram Eldar, Feb 06 2020 *) PROG (PARI) a(n) = {sp = prime(n)-1; while(bigomega(sp) != 2, sp--); sp; } \\ Michel Marcus, Mar 04 2017 CROSSREFS Cf. A001358, A102414, A102440. Sequence in context: A193951 A129854 A088682 * A117003 A335032 A057670 Adjacent sequences:  A102412 A102413 A102414 * A102416 A102417 A102418 KEYWORD nonn AUTHOR Reinhard Zumkeller, Jan 08 2005 STATUS approved

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Last modified April 12 00:05 EDT 2021. Contains 342910 sequences. (Running on oeis4.)