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A084716 a(1) = 1, a(n) = smallest multiple of a(n-1) > a(n-1) such that a(n) + 1 is a prime. 3
1, 2, 4, 12, 36, 72, 432, 1296, 2592, 10368, 72576, 508032, 1524096, 12192768, 73156608, 146313216, 438939648, 2633637888, 23702740992, 142216445952, 1991030243328, 37829574623232, 416125320855552 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..23.

MATHEMATICA

a[1] = 1; a[n_] := a[n] = Catch[For[k = 2, True, k++, an = k*a[n - 1]; If[PrimeQ[an + 1], Throw[an]]]]; Table[a[n], {n, 1, 23}] (* Jean-Fran├žois Alcover, Nov 27 2012 *)

CROSSREFS

Cf. A084717, A084718, A036012.

Sequence in context: A112083 A089965 A202727 * A241208 A149837 A149838

Adjacent sequences:  A084713 A084714 A084715 * A084717 A084718 A084719

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Jun 11 2003

EXTENSIONS

Edited by Don Reble (djr(AT)nk.ca), Jun 19 2003

STATUS

approved

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Last modified December 4 06:30 EST 2016. Contains 278749 sequences.