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A030470
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Numbers k such that k concatenated with k+1, k+2, k+3 is prime.
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3
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4, 14, 20, 34, 58, 64, 118, 140, 148, 176, 196, 218, 220, 236, 238, 268, 278, 286, 316, 334, 374, 386, 398, 428, 430, 436, 446, 460, 470, 496, 508, 514, 550, 566, 568, 590, 610, 616, 634, 644, 670, 674, 688, 706, 718, 728, 740, 746, 764, 770
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OFFSET
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1,1
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COMMENTS
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All terms must be even; otherwise k+3 would be an even number and thus the concatenation of k, k+1, k+2, and k+3 would not be prime. - Harvey P. Dale, Jul 05 2021
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LINKS
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EXAMPLE
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4567 is prime, so 4 is a term.
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MAPLE
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dcat:= proc(x, y) 10^(1+ilog10(y))*x+y end proc:
filter:= proc(n) isprime(dcat(n, dcat(n+1, dcat(n+2, n+3)))) end proc:
select(filter, [seq(i, i=2..1000, 2)]); # Robert Israel, Apr 01 2021
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MATHEMATICA
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Select[2*Range[400], PrimeQ[FromDigits[Flatten[IntegerDigits/@(Range[ 0, 3]+#)]]]&] (* Harvey P. Dale, Jul 05 2021 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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