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 A084400 a(1) = 1; for n>1, a(n) = smallest number that does not divide the product of all previous terms. 14
 1, 2, 3, 4, 5, 7, 9, 11, 13, 16, 17, 19, 23, 25, 29, 31, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 107, 109, 113, 121, 127, 131, 137, 139, 149, 151, 157, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS All numbers of the form p^(2^k) are members. Except for the first term, same as A050376. - David Wasserman, Dec 22 2004 Also, the lexicographically earliest sequence of distinct positive integers such that the number of divisors of the product of n initial terms (for any n) is a power of 2. - Ivan Neretin, Aug 12 2015 LINKS Giovanni Resta, Table of n, a(n) for n = 1..10000 PROG (PARI) find(pv)=k = 1; while (! (pv % k), k++); return (k); lista(nn) = print1(pv=1, ", "); for (i=1, nn, nv = find(pv); pv *= nv; print1(nv, ", ")) \\ Michel Marcus, Aug 12 2015 (PARI) A209229(n)=if(n%2, n==1, isprimepower(n)) is(n)=A209229(isprimepower(n)) || n==1 \\ Charles R Greathouse IV, Oct 19 2015 CROSSREFS Cf. A000040 (primes), A026416, A000028, A066724, A026477, A050376. Sequence in context: A009087 A026477 A079852 * A050376 A280257 A050198 Adjacent sequences:  A084397 A084398 A084399 * A084401 A084402 A084403 KEYWORD nonn AUTHOR Amarnath Murthy, May 31 2003 EXTENSIONS More terms from Patrick De Geest, Jun 05 2003 STATUS approved

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Last modified December 6 14:15 EST 2019. Contains 329806 sequences. (Running on oeis4.)