A105091 - OEIS

%I #12 Sep 02 2024 08:39:45

%S 33,133,253,383,537,691,829,1003,1169,1333,1495,1703,1855,2015,2217,

%T 2417,2589,2781,2977,3143,3313,3537,3725,3899,4157,4349,4511,4713,

%U 4871,5113,5317,5563,5747,5987,6183,6377,6607,6827,7025,7187,7391,7673,7927

%N Sum of the right diagonal in ordered 3 X 3 prime squares.

%C An ordered 3 X 3 prime square is 9 consecutive primes arranged in a square:

%C     p(9n-8) p(9n-7) p(9n-6)

%C     p(9n-5) p(9n-4) p(9n-3)

%C     p(9n-2) p(9n-1) p(9n)

%C The right diagonal is p(9n-6) p(9n-4) p(9n-2).

%F a(n) = A000040(9*n-6) + A000040(9*n-4) + A000040(9*n-2). - _Jason Yuen_, Sep 01 2024

%e The first 3 X 3 prime square

%e   2  3  5

%e   7 11 13

%e  17 19 23

%e sum of right diagonal = 5 + 11 + 17 = 33 the first entry.

%o (PARI) sum3x3right(n) = { local(x,j,s); forstep(x=0,n,9, s=0; forstep(j=3,7,2, s += prime(x+j); ); print1(s",") ) }

%Y Cf. A000040, A105090.

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, Apr 07 2005