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 A032682 Numbers k such that k surrounded by digit '1' is a prime. 14
 0, 3, 5, 8, 9, 15, 17, 18, 20, 23, 29, 30, 32, 36, 38, 45, 47, 48, 51, 53, 57, 60, 62, 72, 74, 80, 81, 83, 86, 87, 90, 93, 95, 107, 113, 116, 117, 125, 126, 131, 132, 135, 141, 147, 149, 155, 162, 168, 170, 173, 180, 182, 183, 194, 197, 198, 201, 204, 207, 210 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Daniel Starodubtsev, Table of n, a(n) for n = 1..10000 MAPLE t0:=[]; u0:=[]; for n from 1 to 100 do t1:=cat(1, n, 1); t1:=convert(t1, decimal, 10); if isprime(t1) then t0:=[op(t0), n]; u0:=[op(u0), t1]; fi; od: t0; MATHEMATICA Select[Range[0, 210], PrimeQ[FromDigits[Join[{1}, IntegerDigits[#], {1}]]]&] (* Jayanta Basu, Jun 02 2013 *) PROG (Python) from sympy import isprime print([i for i in range(200) if isprime(int('1' + str(i) + '1'))]) # Daniel Starodubtsev, Apr 05 2020 CROSSREFS The primes are in A099677. Cf. A032686. Sequence in context: A308405 A331314 A018804 * A022769 A343114 A349679 Adjacent sequences: A032679 A032680 A032681 * A032683 A032684 A032685 KEYWORD nonn,base AUTHOR Patrick De Geest, May 15 1998 STATUS approved

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Last modified May 30 20:23 EDT 2023. Contains 363061 sequences. (Running on oeis4.)