A033938 Palindromic primes n such that the period of 1/n is a palindrome.

2, 3, 5, 7, 11, 101, 787, 929, 32323, 36563, 70507, 72727, 74747, 78487, 78787, 1278721, 3212123, 3218123, 3252523, 3256523, 3258523, 3272723, 3618163, 3670763, 3698963, 7014107, 7036307, 7096907, 7434347, 7436347, 7472747

Offset

1,1

Comments

Number of terms < 10^n: 4, 5, 8, 8, 15, 15, 40, 40, 117, 117, 441, 441, 1720, 1720, 7152, 7152, 33598, 33598, ..., . - Robert G. Wilson v, Jul 19 2015

References

Calculated by Jud McCranie

Links

Robert G. Wilson v, Table of n, a(n) for n = 1..33599

Mathematica

(* copy nthPalindrome from A002113*) palQ[n_] := Block[{}, Reverse[idn = IntegerDigits@ n] == idn]; digitCycleLength[r_Rational, b_Integer?Positive] := MultiplicativeOrder[b, FixedPoint[Quotient[#, GCD[#, b]] &, Denominator[r]]] (* from Mathematica help file for MultiplicativeOrder *); k = 1; lst = {}; While[k < 10000, p = nthPalindrome[k]; If[ PrimeQ@ p && palQ[ digitCycleLength[1/p, 10]], AppendTo[lst, p]]; k++]; lst (* Robert G. Wilson v, Jul 19 2015 *)

Crossrefs

Cf. A002385 and A033939.

Sequence in context: A109574 A084837 A062352 * A069598 A049575 A070028

Adjacent sequences: A033935 A033936 A033937 * A033939 A033940 A033941

Keyword

nonn,base

Author

Proposed by G. L. Honaker, Jr.

Status

approved