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A030470 Numbers k such that k concatenated with k+1, k+2, k+3 is prime. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

4567 is prime, so 4 is a term.

MAPLE

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

MATHEMATICA

Select[2*Range[400], PrimeQ[FromDigits[Flatten[IntegerDigits/@(Range[ 0, 3]+#)]]]&] (* Harvey P. Dale, Jul 05 2021 *)

PROG

(PARI) is(n)=isprime(eval(Str(n, n+1, n+2, n+3))) \\ Charles R Greathouse IV, Jun 12 2017

CROSSREFS

Sequence in context: A139330 A051448 A075319 * A326004 A297358 A267768

Adjacent sequences: A030467 A030468 A030469 * A030471 A030472 A030473

KEYWORD

nonn,base

AUTHOR

Patrick De Geest

STATUS

approved

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Last modified December 4 19:07 EST 2022. Contains 358563 sequences. (Running on oeis4.)