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A267487 Primes p such that A001221(p+1)^(p-1) == 1 (mod p^2). 1
2, 3, 7, 31, 127, 1093, 3511, 8191, 131071, 524287 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

No further terms up to 10^9.

Are all terms of A000668 and A001220 in the sequence?

Does the sequence contain any terms not in A000668 or A001220 other than 2?

LINKS

Table of n, a(n) for n=1..10.

MAPLE

isA267487 := proc(p)

    if isprime(p) then

        A001221(p+1) ;

        simplify(modp(% &^ (p-1), p^2) =1 );

    else

        false;

    end if;

end proc:

p := 2;

for i from 1 do

    if isA267487(p) then

        printf("%d\n", p) ;

    end if;

    p := nextprime(p) ;

end do: # R. J. Mathar, Jan 23 2016

MATHEMATICA

Select[Prime[Range[3200]], Mod[PrimeNu[# + 1], #^2]^(# - 1) == 1 &] (* G. C. Greubel, Apr 25 2017 *)

PROG

(PARI) forprime(p=1, 1e9, if(Mod(omega(p+1), p^2)^(p-1)==1, print1(p, ", ")))

CROSSREFS

Cf. A000668, A001220, A260377.

Sequence in context: A228171 A089359 A239892 * A343733 A081947 A046972

Adjacent sequences:  A267484 A267485 A267486 * A267488 A267489 A267490

KEYWORD

nonn,more

AUTHOR

Felix Fröhlich, Jan 15 2016

STATUS

approved

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Last modified September 27 08:39 EDT 2021. Contains 347689 sequences. (Running on oeis4.)