|
%I #14 Jan 27 2021 14:29:14
%S 188,678,1568,2798,2768,3928,9328,9418,16918,12418,19428,19578,16898,
%T 34698,28028,30988,35878,58528,53908,52318,54938,37308,53098,49888,
%U 49758,68688,65738,74328,96558,100098,95548,121898,119108,117438,104078,140698,156588,143168,222888,226608,196448,160448
%N a(n) is the determinant of the 2 X 2 matrix whose entries (listed by rows) are the n-th prime ending in 1, 3, 7, 9 respectively.
%C All terms == 8 (mod 10).
%C Are there negative terms? The first 10^7 are positive.
%H Robert Israel, <a href="/A335592/b335592.txt">Table of n, a(n) for n = 1..10000</a>
%e The first primes ending in 1,3,7,9 are 11,3,7,19, so a(1) = 11*19 - 3*7 = 188.
%e The second primes ending in 1,3,7,9 are 31,13,17,29, so a(2) = 31*29 - 13*17 = 678.
%e The third primes ending in 1,3,7,9 are 41,23,37,59, so a(3) = 41*59 - 23*37 = 1568.
%p R:= NULL:
%p L:= [-9,-7,-3,-1]:
%p for k from 1 to 100 do
%p for i from 1 to 4 do
%p for x from L[i]+10 by 10 do until isprime(x);
%p L[i]:= x;
%p od;
%p R:= R, L[1]*L[4]-L[2]*L[3];
%p od:
%p R;
%Y Cf. A335581, A335593, A336738.
%K nonn,base,look
%O 1,1
%A _J. M. Bergot_ and _Robert Israel_, Jan 27 2021
|
