login
Lesser of consecutive prime pairs whose last digits differ by 4.
0

%I #6 Feb 02 2025 21:17:42

%S 13,43,47,103,113,157,163,167,193,223,257,293,313,367,463,557,587,607,

%T 613,643,647,673,677,727,773,823,853,863,883,947,953,977,1093,1097,

%U 1117,1187,1213,1217,1303,1367,1423,1483,1583,1657,1663,1693,1747,1777,1783

%N Lesser of consecutive prime pairs whose last digits differ by 4.

%C Conjecture: The number of terms in this sequence is infinite.

%e The last digits of the consecutive prime pair 13 and 17 differ by 4 so 13 is in the table.

%t Select[Prime[Range[277]],Abs[Mod[#,10]-Mod[NextPrime[#],10]]==4&] (* _James C. McMahon_, Feb 02 2025 *)

%o (PARI) \d can be 2,4,6,8 primediffd(n,d) = { forprime(x=3,n, y=abs((nextprime(x+1)%10-x%10)); if(y==d,print1(x",") ) ) }

%K easy,nonn,base,less,changed

%O 2,1

%A _Cino Hilliard_, May 19 2007