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 A054258 Concatenation of n in base 2 up to base 10 and n in base 10 down to base 2 is prime, all numbers are interpreted as decimals. 3
 2607, 4007, 4069, 7597, 12411, 13583, 23041, 31113, 32619, 46187, 48469, 55777, 61411, 64387, 71143, 73837, 84761, 103559, 123797, 124043, 126613, 136509, 142019, 147449, 183981, 186889, 200183, 204219, 214819, 221101, 224123, 230977, 235493, 249049, 256489 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Michael S. Branicky, Table of n, a(n) for n = 1..10000 EXAMPLE a(1) = 2607 is a term since both 10100010111110120120220233404122002310413505735162607 and 26073516505710413200234041222023310120120101000101111 are prime. MATHEMATICA Select[Range[250000], AllTrue[{FromDigits[Flatten[Table[IntegerDigits[#, b], {b, 2, 10}]]], FromDigits[ Flatten[Table[IntegerDigits[#, b], {b, 10, 2, -1}]]]}, PrimeQ]&] (* Harvey P. Dale, May 28 2023 *) PROG (Python) from gmpy2 import digits, is_prime def ok(n): return is_prime(int("".join(digits(n, b) for b in list(range(2, 11))))) and is_prime(int("".join(digits(n, b) for b in list(range(10, 1, -1))))) print([k for k in range(234567) if ok(k)]) # Michael S. Branicky, May 28 2023 CROSSREFS Intersection of A054256 and A054257. Sequence in context: A212083 A236889 A254695 * A236666 A252341 A235777 Adjacent sequences: A054255 A054256 A054257 * A054259 A054260 A054261 KEYWORD nonn,base AUTHOR Patrick De Geest, Feb 15 2000 EXTENSIONS Offset changed to 1 and a(33) and beyond from Michael S. Branicky, May 28 2023 STATUS approved

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Last modified October 4 09:13 EDT 2023. Contains 365873 sequences. (Running on oeis4.)