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A030470 Numbers n such that n concatenated with n+1, n+2, n+3 is prime. 3


%S 4,14,20,34,58,64,118,140,148,176,196,218,220,236,238,268,278,286,316,

%T 334,374,386,398,428,430,436,446,460,470,496,508,514,550,566,568,590,

%U 610,616,634,644,670,674,688,706,718,728,740,746,764,770

%N Numbers n such that n concatenated with n+1, n+2, n+3 is prime.

%H Robert Israel, <a href="/A030470/b030470.txt">Table of n, a(n) for n = 1..10000</a>

%e E.g. 4567 is prime.

%p dcat:= proc(x,y) 10^(1+ilog10(y))*x+y end proc:

%p filter:= proc(n) isprime(dcat(n,dcat(n+1,dcat(n+2,n+3)))) end proc:

%p select(filter, [seq(i,i=2..1000,2)]); # _Robert Israel_, Apr 01 2021

%o (PARI) is(n)=isprime(eval(Str(n,n+1,n+2,n+3))) \\ _Charles R Greathouse IV_, Jun 12 2017

%K nonn,base

%O 1,1

%A _Patrick De Geest_

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Last modified May 16 15:55 EDT 2021. Contains 343949 sequences. (Running on oeis4.)