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A094454 First of 9 consecutive primes in a 3 X 3 spiral wherein the mean of all 8 sums is prime. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified April 18 10:56 EDT 2021. Contains 343087 sequences. (Running on oeis4.)