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

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A339536 Numbers b > 1 such that the smallest seven primes, i.e., 2, 3, 5, 7, 11, 13 and 17 are base-b Wieferich primes. 6
4486949, 4651993, 4941649, 5571593, 11903257, 19397501, 19841257, 19942001, 20610901, 21530501, 25793893, 42969601, 44404093, 46336949, 51509701, 52786493, 53740457, 54561401, 56120257, 56904857, 63789749, 64028593, 65497301, 65666449, 68441957, 72582101 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..26.

PROG

(PARI) is(n) = forprime(p=1, 17, if(Mod(n, p^2)^(p-1)!=1, return(0))); 1

CROSSREFS

Cf. A256236. Row 1 of A319064.

Cf. smallest k primes are base-b Wieferich primes: A339531 (k=2), A339532 (k=3), A339533 (k=4), A339534 (k=5), A339535 (k=6), A339537 (k=8).

Sequence in context: A244575 A105649 A015337 * A319064 A344831 A183679

Adjacent sequences:  A339533 A339534 A339535 * A339537 A339538 A339539

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Dec 08 2020

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 December 2 05:01 EST 2021. Contains 349437 sequences. (Running on oeis4.)