A084401 n-th partial product + 1 is a prime, where a(n)>1 for n>1.

1, 2, 2, 3, 3, 2, 6, 3, 2, 4, 7, 7, 3, 8, 6, 2, 3, 6, 9, 6, 14, 19, 11, 4, 4, 19, 4, 13, 3, 10, 13, 15, 4, 11, 9, 2, 5, 26, 19, 52, 21, 20, 63, 4, 19, 17, 6, 29, 19, 3, 5, 51, 11, 14, 15, 7, 12, 44, 34, 7, 21, 32, 3, 22, 10, 19, 19, 7, 20, 4, 22, 4, 17, 35, 47, 40, 14, 5, 14, 36, 39, 16

Offset

1,2

Comments

Except for the first term, same as A036012. - David Wasserman, Dec 22 2004

Links

Table of n, a(n) for n=1..82.

Example

1+1 =2, 1*2+1=3, 1*2*2 +1=5 etc. are primes.

Mathematica

a[1] = p = 1; a[n_] := a[n] = Catch[For[k = 2, True, k++, If[PrimeQ[p*k + 1], p = p*k; Throw[k]]]]; Table[a[n], {n, 1, 82}] (* Jean-François Alcover, May 14 2012 *)

Crossrefs

Cf. A084402.

Sequence in context: A045796 A127684 A036012 * A236465 A131619 A048485

Adjacent sequences: A084398 A084399 A084400 * A084402 A084403 A084404

Keyword

nonn

Author

Amarnath Murthy, May 31 2003

Extensions

More terms from David Wasserman, Dec 22 2004

Status

approved