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 A287301 Primes that can be generated by the concatenation in base 3, in descending order, of two consecutive integers read in base 10. 0
 3, 7, 11, 59, 79, 89, 307, 419, 503, 587, 643, 727, 2377, 2459, 3361, 3607, 3853, 4099, 4591, 4673, 4919, 5657, 5821, 5903, 6067, 20983, 21227, 22447, 22691, 23911, 26107, 26839, 28547, 30011, 31231, 31963, 32939, 33427, 34159, 34403, 36599, 37087, 41479, 42943 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE 1 and 2 in base 3 are 1 and 2 and concat(2,1) = 21 in base 10 is 7; 2 and 3 in base 3 are 2 and 10 and concat(10,2) = 102 in base 10 is 11. MAPLE with(numtheory): P:= proc(q, h) local a, b, c, d, k, n; if q=0 then 3 else a:=convert(q+1, base, h); b:=convert(q, base, h); c:=[op(a), op(b)]; d:=0; for k from nops(c) by -1 to 1 do d:=h*d+c[k]; od; if isprime(d) then d; fi; fi; end: seq(P(i, 3), i=0..1000); MATHEMATICA With[{b = 3}, Select[Map[FromDigits[Flatten@ IntegerDigits[#, b], b] &, Reverse /@ Partition[Range[0, 150], 2, 1]], PrimeQ]] (* Michael De Vlieger, May 23 2017 *) CROSSREFS Cf. A000040, A052089. Sequence in context: A005372 A125220 A016081 * A105762 A057469 A247229 Adjacent sequences: A287298 A287299 A287300 * A287302 A287303 A287304 KEYWORD nonn,base,easy AUTHOR Paolo P. Lava, May 23 2017 STATUS approved

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Last modified February 7 22:10 EST 2023. Contains 360132 sequences. (Running on oeis4.)