OFFSET
1,1
COMMENTS
Partition the primes into consecutive and non-overlapping groups of nine primes and take the total of each group. - Harvey P. Dale, Sep 06 2018
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
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, ...
EXAMPLE
The first 3 X 3 prime square
2 3 5
7 11 13
17 19 23
adds up to 100 the first entry in the table.
MATHEMATICA
With[{nn=40}, Total/@Partition[Prime[Range[9nn]], 9]] (* or *) Table[ Total[ Prime[Range[9i-8, 9i]]], {i, 40}] (* Harvey P. Dale, Sep 06 2018 *)
PROG
(PARI) sumsq3x3(n) = { local(x, j, s); forstep(x=0, n, 9, s=0; for(j=1, 9, s += prime(x+j); ); print1(s", ") ) }
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Apr 07 2005
STATUS
approved