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 A236537 Primes whose binary and ternary representations are also prime when read in decimal. 6
 157, 199, 229, 313, 367, 523, 883, 1483, 2683, 2971, 3109, 3253, 3637, 4093, 4357, 4363, 4729, 4951, 5119, 5827, 6529, 9241, 10909, 11527, 13477, 15271, 15919, 18439, 19273, 19483, 22921, 24019, 29833, 31237, 31573, 32803, 35863, 35899, 36109, 36973, 39799 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS K. D. Bajpai, Table of n, a(n) for n = 1..2115 EXAMPLE 157 is prime and appears in the sequence. Its representation in binary = 10011101 and in ternary = 12211 are also prime when read in decimal. 313 is prime and appears in the sequence. Its representation in binary = 100111001 and in ternary = 102121 are also prime when read in decimal. MATHEMATICA t={}; n=1; While[Length[t] < 50, n=NextPrime[n]; If[PrimeQ[FromDigits[IntegerDigits[n, 2]]] && PrimeQ[FromDigits[IntegerDigits[n, 3]]], AppendTo[t, n]]]; t PROG (PARI) base_b(n, b) = my(s=[], r, x=10); while(n>0, r = n%b; n = n\b; s = concat(r, s)); eval(Pol(s)) s=[]; forprime(p=2, 40000, if(isprime(base_b(p, 2)) && isprime(base_b(p, 3)), s=concat(s, p))); s \\ Colin Barker, Jan 28 2014 CROSSREFS Cf. A000040 (prime numbers), A065720 (primes: binary representation is also prime), A236365 (primes: binary and octal representation is also prime), A236512 (primes: base 2, 3, 4 and 5 representation are also prime). Sequence in context: A178092 A140035 A007356 * A048927 A163490 A142063 Adjacent sequences:  A236534 A236535 A236536 * A236538 A236539 A236540 KEYWORD nonn,base AUTHOR K. D. Bajpai, Jan 28 2014 STATUS approved

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Last modified December 14 05:36 EST 2019. Contains 329978 sequences. (Running on oeis4.)