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A026443 a(n) = least positive integer > a(n-1) and not a(i)*a(j)+2 for 1<=i<j<=n. 11
1, 2, 3, 6, 7, 10, 11, 15, 18, 19, 25, 26, 29, 30, 33, 34, 37, 41, 42, 45, 46, 49, 50, 53, 57, 58, 61, 64, 65, 69, 73, 74, 78, 81, 82, 85, 88, 91, 95, 96, 99, 103, 106, 109, 114, 115, 119, 120, 123, 126, 127, 131, 134, 138, 139, 142, 143 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..1000

MATHEMATICA

a = {1, 2}; used = {a[[1]]*a[[2]] + 2}; Do[k = a[[-1]] + 1;

While[MemberQ[used, k], k++]; used = Union[used, k*a + 2];

AppendTo[a, k], {n, 3, 60}]; a (* Ivan Neretin, Mar 06 2016 *)

CROSSREFS

Similar sequences with different starting conditions: A026444 (1,3), A026445 (2,3), A026446 (2,4), A026447 (3,4).

Related sequences with definition using any products (not necessarily distinct) and with various starting conditions: A026448 (1,2), A026449 (1,3), A026450 (2,3), A026451 (2,4), A026452 (3,4).

Sequence in context: A073170 A014689 A117206 * A204323 A278965 A032858

Adjacent sequences:  A026440 A026441 A026442 * A026444 A026445 A026446

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified May 25 15:17 EDT 2019. Contains 323569 sequences. (Running on oeis4.)