A109854 - OEIS

A109854

Least K such that K*(3^(n+j))+1 is prime for j=0 to 4.

20, 110, 110, 20980, 29580, 9860, 150780, 50260, 217490, 657770, 426650, 1999330, 2942960, 1295490, 431830, 437570, 436450, 7564120, 6449730

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OFFSET

1,1

LINKS

EXAMPLE

20*(3^(1+0))+1=61 prime

20*(3^(1+1))+1=181 prime

20*(3^(1+2))+1=541 prime

20*(3^(1+3))+1=1621 prime

20*(3^(1+4))+1=4861 prime

so for n=1 K=20.

CROSSREFS

KEYWORD

nonn

AUTHOR

Pierre CAMI, Aug 31 2005

STATUS

approved