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 A069280 19-almost primes (generalization of semiprimes). 26
 524288, 786432, 1179648, 1310720, 1769472, 1835008, 1966080, 2654208, 2752512, 2883584, 2949120, 3276800, 3407872, 3981312, 4128768, 4325376, 4423680, 4456448, 4587520, 4915200, 4980736, 5111808, 5971968, 6029312, 6193152 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Product of 19 not necessarily distinct primes. Divisible by exactly 19 prime powers (not including 1). LINKS D. W. Wilson, Table of n, a(n) for n = 1..10000 Eric Weisstein's World of Mathematics, Almost Prime. FORMULA Product p_i^e_i with Sum e_i = 19. PROG (PARI) k=19; start=2^k; finish=8000000; v=[] for(n=start, finish, if(bigomega(n)==k, v=concat(v, n))); v CROSSREFS Sequences listing r-almost primes, that is, the n such that A001222(n) = r: A000040 (r = 1), A001358 (r = 2), A014612 (r = 3), A014613 (r = 4), A014614 (r = 5), A046306 (r = 6), A046308 (r = 7), A046310 (r = 8), A046312 (r = 9), A046314 (r = 10), A069272 (r = 11), A069273 (r = 12), A069274 (r = 13), A069275 (r = 14), A069276 (r = 15), A069277 (r = 16), A069278 (r = 17), A069279 (r = 18), this sequence (r = 19), A069281 (r = 20). - Jason Kimberley, Oct 02 2011 Sequence in context: A069394 A289480 A222530 * A017702 A010807 A236227 Adjacent sequences:  A069277 A069278 A069279 * A069281 A069282 A069283 KEYWORD nonn AUTHOR Rick L. Shepherd, Mar 13 2002 STATUS approved

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Last modified December 12 19:33 EST 2018. Contains 318081 sequences. (Running on oeis4.)