A088123 Let f(n,x) = 1 + 2x + 3x^2 + 5x^3 + 7x^4 + ... + prime(n)*x^n; a(n) = smallest value of x such that f(n,x) is a prime, or 0 if no such prime exists.

1, 2, 1, 6, 1, 6, 1, 8, 1, 74, 6, 6, 1, 2, 11, 102, 20, 88, 1, 52, 10, 18, 2, 56, 1, 26, 37, 216, 1, 78, 1, 28, 21, 160, 3, 276, 30, 1542, 42, 598, 20, 20, 333, 186, 8, 82, 11, 90, 1, 246, 1, 240, 83, 58, 9, 76, 1, 16, 21, 700, 60, 10, 87, 250, 62, 406, 2, 502, 140, 186, 1293, 578

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Example

a(4) = 6 as, A088122(4) = 10273 = f(4,6).

Mathematica

Table[Clear[x, n, eq]; eq=Total[Table[Prime[n]x^n, {n, t}]]+1; x=1; While[ !PrimeQ[ eq], x++]; x, {t, 80}] (* Harvey P. Dale, Apr 27 2013 *)

Crossrefs

Cf. A088122.

Sequence in context: A318503 A328580 A362784 * A050932 A366573 A366570

Adjacent sequences: A088120 A088121 A088122 * A088124 A088125 A088126

Keyword

nonn

Author

Amarnath Murthy, Sep 25 2003

Extensions

More terms from Tom Mueller, May 04 2004

More terms from David Wasserman, Jul 25 2005

Status

approved