cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A286333 Primes p where all the cyclic shifts of their digits to the left also produce primes except the last one before reaching p again.

Original entry on oeis.org

19, 23, 29, 41, 43, 47, 53, 59, 61, 67, 83, 89, 101, 103, 107, 127, 149, 157, 163, 181, 191, 307, 317, 331, 359, 367, 701, 709, 727, 739, 757, 761, 787, 797, 907, 937, 941, 947, 983, 1103, 1109, 1123, 1181, 1301, 1319, 1327, 1949, 1951, 1979, 1987, 1993, 3121, 3187, 3361, 3373, 3701
Offset: 1

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Author

Mikk Heidemaa, May 07 2017

Keywords

Comments

a(144) = 733793111393, a(145) is larger than 10^16 (if it exists).
Can be considered as primitive terms of A270083, i.e. terms in A270083 can be obtained by cyclic shifts of the digits of terms in this sequence (and leading zeros are not allowed). - Chai Wah Wu, May 21 2017

Examples

			1123 is a member as all the cyclic shifts of its digits to the left result are primes (1231, 2311) except the last one (3112) before reaching the original prime.
		

Crossrefs

Cf. A270083 (subsequence of), A286415.

Programs

  • Mathematica
    cyclDigs[k_]:= FromDigits/@ NestList[RotateLeft, IntegerDigits[k], IntegerLength[k]-1]; lftSftNearCircPrmsInBtw[m_, n_]:= ParallelMap[If[ AllTrue[Most[cyclDigs[#]], PrimeQ] && Not@ PrimeQ[Last[cyclDigs[#]]], #, Nothing] &, Prime @ Range[PrimePi[m], PrimePi[n]]];
    lftSftNearCircPrmsInBtw[19, 10^7]
  • Python
    from itertools import product
    from sympy import isprime
    A286333_list = []
    for l in range(14):
        for w in product('1379',repeat=l):
            for d in '0123456789':
                for t in '1379':
                    s = ''.join(w)+d+t
                    n = int(s)
                    for i in range(l+1):
                        if not isprime(int(s)):
                            break
                        s = s[1:]+s[0]
                    else:
                        if n > 10 and not isprime(int(s)):
                            A286333_list.append(n) # Chai Wah Wu, May 21 2017