login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A172130 a(n) = the smallest k such that n(n+1)(n+2)...(n+k-1)-1 is a prime 1
3, 2, 1, 1, 2, 1, 3, 1, 2, 2, 2, 1, 2, 1, 2, 2, 3, 1, 2, 1, 2, 3, 3, 1, 17, 2, 4, 2, 6, 1, 2, 1, 10, 3, 2, 9, 3, 1, 2, 3, 2, 1, 4, 1, 2, 2, 3, 1, 4, 2, 8, 7, 2, 1, 2, 2, 3, 3, 2, 1, 11, 1, 3, 2, 2, 2, 5, 1, 3, 2, 11, 1, 4, 1, 3, 2, 7, 7, 5, 1, 4, 38, 2, 1, 2, 2, 7, 9, 2, 1, 4, 4, 2, 2, 4, 2, 3, 1, 14, 2, 2, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(534) = 624 is particularly large.

LINKS

Table of n, a(n) for n=1..103.

MATHEMATICA

a[n_] := Block[{}, For[s = n; k = 1, ! PrimeQ[s - 1], s *= n + k; k++ ]; k]; Table[a[n], {n, 1, 300}]

CROSSREFS

Cf. A172125, A172133, A087564

Sequence in context: A247044 A083663 A085427 * A202449 A326613 A288627

Adjacent sequences:  A172127 A172128 A172129 * A172131 A172132 A172133

KEYWORD

nonn

AUTHOR

Cheng Zhang (cz1(AT)rice.edu), Jan 26 2010, Mar 03 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 2 06:37 EST 2021. Contains 341744 sequences. (Running on oeis4.)