A094454 First of 9 consecutive primes in a 3 X 3 spiral wherein the mean of all 8 sums is prime.

3, 457, 563, 811, 1571, 1889, 2203, 2411, 2917, 3119, 3209, 3931, 4079, 4357, 4507, 4889, 5087, 5153, 5387, 5441, 5749, 5939, 6043, 6421, 6871, 6991, 7079, 7699, 8929, 9283, 9467, 9677, 10151, 11071, 11411, 12197, 12253, 12919, 13309, 13327, 13337

Offset

1,1

Links

Table of n, a(n) for n=1..41.

Harvey Heinz, pattern and program

Formula

Arrange 9 consecutive primes in a 3 X 3 grid wherein IBC, HAD, GFE are the first, second and third rows of horizontal primes. Then sum the rows horizontally, vertically and along the two main diagonals. Total the 8 sums, divide by 8 and if the mean is integral and prime, add to the sequence.

Example

a(1)=3 because 3 is the first of 9 primes arranged in a 3 X 3 grid wherein the mean of all 8 sums is 41, prime

Crossrefs

Cf. A094455.

Sequence in context: A139999 A140870 A157601 * A261004 A157587 A054702

Adjacent sequences: A094451 A094452 A094453 * A094455 A094456 A094457

Keyword

easy,nonn

Author

Enoch Haga, May 05 2004

Status

approved