A105087 - OEIS

A105087

Absolute difference between the sums of the left and right diagonals of ordered 2 X 2 prime squares.

1, 0, 0, 4, 2, 0, 0, 0, 0, 0, 0, 10, 4, 4, 2, 6, 2, 4, 2, 0, 0, 4, 10, 0, 6, 4, 0, 4, 8, 2, 6, 0, 2, 2, 2, 6, 6, 0, 0, 6, 2, 0, 2, 8, 4, 0, 0, 12, 4, 6, 10, 14, 2, 2, 28, 4, 4, 2, 6, 8, 2, 2, 0, 4, 14, 20, 10, 4, 0, 8, 6, 0, 4, 2, 14, 0, 4, 8, 0, 4, 4, 16, 10, 12, 2, 2, 0, 0, 2, 6, 8, 20, 6, 20, 6, 2, 2, 0

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OFFSET

1,4

COMMENTS

The first 2 X 2 prime square of a set of ordered 2 X 2 prime squares begins with 2. Just a 2 X 2 prime square is any 4 consecutive primes arranged in a square formation.

LINKS

Table of n, a(n) for n=1..98.

FORMULA

A 2 X 2 ordered prime square is 4 consecutive primes arranged in a square of the form p(4n-3) p(4n-2) p(4n-1) p(4n) where n=1, 2, ... and Left diagonal is p(4n+1), p(4n) Right diagonal is p(4n+2), p(4n+3).

EXAMPLE

The 4th prime square is

41 43

47 53

sum of left diagonal = 41+53 = 94

sum of right diagonal = 43+47 = 90

difference = 4

So 4 is the 4th term.

PROG

(PARI) diffdiag(n) = { local(x, d1, d2); forstep(x=1, n, 4, d1=prime(x)+ prime(x+3); d2=prime(x+1)+ prime(x+2); print1(abs(d1-d2)", ") ) }

CROSSREFS

Sequence in context: A036115 A056582 A167891 * A238012 A324802 A320647

Adjacent sequences: A105084 A105085 A105086 * A105088 A105089 A105090

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Apr 07 2005

STATUS

approved