A105090 Sum of the left diagonal in ordered 3 X 3 prime squares.

36, 133, 253, 389, 533, 679, 841, 1007, 1175, 1327, 1489, 1703, 1859, 2021, 2209, 2405, 2571, 2769, 2977, 3139, 3319, 3545, 3733, 3905, 4135, 4361, 4525, 4721, 4891, 5099, 5319, 5549, 5743, 5987, 6177, 6361, 6599, 6813, 7021, 7193, 7425, 7675, 7927

Offset

1,1

Links

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

Formula

An ordered 3 X 3 prime square is 9 consecutive primes arranged in a square of the form 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) n=1, 2, .. Left diagonal is p(9n-8) p(9n-4) p(9n)

Example

The first 3 X 3 prime square
2 3 5
7 11 13
17 19 23
sum of left diagonal = 2 + 11 + 23 = 36 the first entry.

Prog

(PARI) sum3x3left(n) = { local(x, j, s); forstep(x=0, n, 9, s=0; forstep(j=1, 9, 4, s += prime(x+j); ); print1(s", ") ) }

Crossrefs

Sequence in context: A260130 A155708 A196891 * A254284 A076578 A044368

Adjacent sequences: A105087 A105088 A105089 * A105091 A105092 A105093

Keyword

easy,nonn

Author

Cino Hilliard, Apr 07 2005

Status

approved