A288021 - OEIS

%I #9 Jun 14 2017 11:10:31

%S 7,19,37,67,79,97,109,127,229,277,307,349,379,397,439,457,487,499,739,

%T 757,769,859,877,907,937,967,1009,1087,1279,1297,1429,1447,1489,1549,

%U 1567,1579,1597,1609,1867,1999,2137,2239,2269,2347,2377,2389,2437,2539,2617,2659,2689,2707,2749,2797,2857

%N Prime p1 of consecutive primes p1, p2, where p2 - p1 = 4, and p1, p2 are in different decades.

%C The unit digits of the numbers in the sequence are 7's or 9's.

%e 7 is in this sequence since pair (7,11) is the first with difference 4 spanning a multiple of 10.

%t a288021[n_] := Map[Last, Select[Map[{NextPrime[#, 1], NextPrime[#, -1]}&, Range[10, n, 10]], First[#]-Last[#]==4&]]

%t a288021[3000] (* data *)

%Y Cf. A001359, A023201, A023203, A031924, A031925, A031928, A046117, A046132, A158277, A158861, A160370, A160440, A160500, A287049, A287050, A060229, A288022, A288024.

%K nonn

%O 1,1

%A _Hartmut F. W. Hoft_, Jun 04 2017