A093484 Beginning with 2, a(n+1) is obtained as the least prime of the form a(n)*(m)*(m+1)*(m+2)...(m+k) +1 where a(n) was obtained as the least prime of the form a(n-1)*(r)*(r+1)*(r+2)...(m-1) +1 and so on.

2, 5, 61, 1831, 1218127681, 20911135539110754710115844300800001, 205118220637830114524967273372102004176647676497164400621440204800001, 6306868169346727750558231922137388394069771110701510995102537435289737085359877256031030165504001

Offset

1,1

Comments

Product [{a(k)-1}/{a(k-1)}]= 2*3*4*5*... for k = 2,3,4,... {(5-1)/2}*{(61-1)/5}*{(1831-1)/61}*... = {2}*{3*4}*{5*6}*....

Some of the larger entries may only correspond to probable primes.

The Magma Calculator (http://magma.maths.usyd.edu.au/calc/) confirms that all terms given above through a(8) are, in fact, prime. - Jon E. Schoenfield, Aug 24 2009

Links

Table of n, a(n) for n=1..8.

Example

a(2) = 2*2 + 1 = 5, a(3) = 5*(3*4) + 1 = 61, a(4) = 61*(5*6) + 1 = 1831.

Crossrefs

Sequence in context: A294528 A363335 A358087 * A375531 A250195 A041069

Adjacent sequences: A093481 A093482 A093483 * A093485 A093486 A093487

Keyword

nonn

Author

Amarnath Murthy, Apr 14 2004

Extensions

More terms from Joshua Zucker, Jul 24 2006

Status

approved