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A033938 Palindromic primes n such that the period of 1/n is a palindrome. 2
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 (list; graph; refs; listen; history; text; internal format)
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
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
KEYWORD
nonn,base
AUTHOR
Proposed by G. L. Honaker, Jr.
STATUS
approved

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Last modified June 20 18:51 EDT 2024. Contains 373532 sequences. (Running on oeis4.)