A092928 Value of k pertaining to A092927: value of k such that n(n-1)(n-2)...(n-k)+1 is the least prime of this form; a(n)=-1 if no such k exists, i.e., A092927(n)=0.

0, 0, 1, 0, 2, 0, 1, 2, 1, 0, 2, 0, 1, 7, 1, 0, 12, 0, -1, 2, 1, 0, 2, 5, 1, 2, 2, 0, 7, 0, 5, 2, 12, 1, 8, 0, 4, 5, 1, 0, 22, 0, 2, 4, 14, 0, 9, 7, 5, 5, 1, 0, 2, 4, 1, 13, 6, 0, 25, 0, 5, 9, 1, 5, 4, 0, 1, 4, 8, 0, 10, 0, 5, 8, 5, 1, 4, 0, 1, 12, 1, 0, 7, 5, 2, 2, 7, 0, 12, 1, 1, 8, 2, 4, 5, 0, 8, 7, 14, 0

Offset

1,5

Comments

Subsidiary sequence: First occurrence of n in this sequence. 1,3,5,...

Links

Table of n, a(n) for n=1..100.

Example

a(8) = 2 as 8*7*6 + 1 = 337 is the least prime of this form.

Prog

(PARI) f(n, k)=prod(i=n-k, n, i)+1; a(n)=for (i=0, n, if(isprime(f(n, i)), print1(i); break()))

Crossrefs

Cf. A092925, A092926, A092927.

Sequence in context: A096800 A036586 A359290 * A321090 A219026 A085097

Adjacent sequences: A092925 A092926 A092927 * A092929 A092930 A092931

Keyword

sign

Author

Amarnath Murthy, Mar 18 2004

Extensions

More terms from Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 19 2004

Corrected and extended by Ray Chandler, Mar 23 2004

Status

approved