A247970 a(n) is the smallest k such that prime(k+i) (mod 6) takes successively the values 5,1,5,1... for i = 0, 1,...,n-1 ending with 1 or 5.
3, 3, 3, 3, 3, 3, 3, 24, 24, 140, 140, 140, 140, 140, 140, 140, 140, 140, 140, 140, 140
Offset: 1
Examples
a(1)= 3 => prime(3) (mod 6)= 5; a(2)= 3 => prime(3) (mod 6)= 5, prime(4) (mod 6) = 1; a(3)= 3 => prime(3) (mod 6)= 5, prime(4) (mod 6)= 1, prime(5) (mod 6)= 5.
Programs
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Maple
with(numtheory): for n from 1 to 35 do : ii:=0: for k from 3 to 10^5 while (ii=0)do : s:=0: for i from 0 to n-1 do: r:=irem(ithprime(k+i),6): if r = irem(5^(i+1),6) then s:=s+1: else fi: od: if s=n and ii=0 then printf ( "%d %d \n",n,k):ii:=1: else fi: od: od:
Comments