A105091 Sum of the right diagonal in ordered 3 X 3 prime squares.

33, 133, 253, 383, 537, 691, 829, 1003, 1169, 1333, 1495, 1703, 1855, 2015, 2217, 2417, 2589, 2781, 2977, 3143, 3313, 3537, 3725, 3899, 4157, 4349, 4511, 4713, 4871, 5113, 5317, 5563, 5747, 5987, 6183, 6377, 6607, 6827, 7025, 7187, 7391, 7673, 7927

Offset

1,1

Comments

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

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

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

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

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

Links

Table of n, a(n) for n=1..43.

Formula

a(n) = A000040(9*n-6) + A000040(9*n-4) + A000040(9*n-2). - Jason Yuen, Sep 01 2024

Example

The first 3 X 3 prime square
  2  3  5
  7 11 13
 17 19 23
sum of right diagonal = 5 + 11 + 17 = 33 the first entry.

Prog

(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", ") ) }

Crossrefs

Cf. A000040, A105090.

Sequence in context: A043502 A044365 A044746 * A158588 A232538 A231758

Adjacent sequences: A105088 A105089 A105090 * A105092 A105093 A105094

Keyword

easy,nonn

Author

Cino Hilliard, Apr 07 2005

Status

approved