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 A156525 Number of n X n arrays of squares of integers, symmetric about main diagonal, with all rows summing to 81. 0
 1, 2, 24, 552, 39012, 11870808, 25684597626, 1292153534554332 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE From Neven Juric, Mar 01 2010: To illustrate a(3) =24: {(0,0,81),(0,81,0),(81,0,0)} {(0,81,0),(81,0,0),(0,0,81)} {(1,16,64),(16,49,16),(64,16,1)} {(1,16,64),(16,64,1),(64,1,16)} {(1,64,16),(64,1,16),(16,16,49)} {(1,64,16),(64,16,1),(16,1,64)} {(9,36,36),(36,9,36),(36,36,9)} {(9,36,36),(36,36,9),(36,9,36)} {(16,1,64),(1,64,16),(64,16,1)} {(16,16,49),(16,49,16),(49,16,16)} {(16,49,16),(49,16,16),(16,16,49)} {(16,64,1),(64,1,16),(1,16,64)} {(36,9,36),(9,36,36),(36,36,9)} {(36,36,9),(36,9,36),(9,36,36)} {(49,16,16),(16,1,64),(16,64,1)}, {(49,16,16),(16,16,49),(16,49,16)} {(49,16,16),(16,49,16),(16,16,49)} {(49,16,16),(16,64,1),(16,1,64)} {(64,1,16),(1,16,64),(16,64,1)} {(64,1,16),(1,64,16),(16,16,49)} {(64,16,1),(16,1,64),(1,64,16)} {(64,16,1),(16,49,16),(1,16,64)} {(81,0,0),(0,0,81),(0,81,0)} {(81,0,0),(0,81,0),(0,0,81)} CROSSREFS Sequence in context: A000186 A210905 A012113 * A170904 A090732 A014298 Adjacent sequences:  A156522 A156523 A156524 * A156526 A156527 A156528 KEYWORD nonn AUTHOR R. H. Hardin Feb 09 2009 STATUS approved

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Last modified January 23 22:43 EST 2021. Contains 340390 sequences. (Running on oeis4.)