A175557 Prime preperiodic part of the decimal expansion of 1/k as k runs through A065502.

5, 2, 5, 41, 3, 2, 2, 2, 17, 13, 11, 89, 7, 5, 5, 5, 41, 3, 3, 347, 3, 3, 3, 29, 2, 2, 2, 2, 26041, 2, 2, 2, 23, 2, 2, 2, 2, 2, 17, 13, 13, 1201, 11, 11, 107, 919, 89, 7, 7, 7, 7, 7, 7, 61, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 41, 4111, 3

Offset

1,1

Comments

Primes in A175555 in the order of appearance.

Multiples of 2 or 5 generate a quotient with a preperiodic sequence of digits, for example 1/24 = 0.041666666..., and 41 is the decimal form of the preperiodic part.

The corresponding values of n are: 2, 5, 20, 24, 28, 36, 44, 50, 56, 72, 88, 112, 136, 168, 184, ...

References

H. Rademacher and O. Toeplitz, Von Zahlen und Figuren (Springer 1930, reprinted 1968), ch. 19, 'Die periodischen Dezimalbrueche'.

Links

Table of n, a(n) for n=1..69.

Example

The prime 347 is in the sequence because 1/288 = .00347222222222222222...
The prime 1201 is in the sequence because 1/832 =.001201 923076 923076 ...

Maple

for n from 1 do
    p := A175555(n) ;
    if isprime(p) then
        print(p) ;
    end if;
end do: # R. J. Mathar, Jul 22 2012

Crossrefs

Cf. A175555, A036275, A065502.

Sequence in context: A248260 A253382 A253384 * A332455 A217702 A018247

Adjacent sequences: A175554 A175555 A175556 * A175558 A175559 A175560

Keyword

nonn,base

Author

Michel Lagneau, Jun 30 2010

Status

approved