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 A111956 Triangle read by rows: T(n,k) = gcd(Lucas(n), Lucas(k)), 1 <= k <= n. 9
 1, 1, 3, 1, 1, 4, 1, 1, 1, 7, 1, 1, 1, 1, 11, 1, 3, 2, 1, 1, 18, 1, 1, 1, 1, 1, 1, 29, 1, 1, 1, 1, 1, 1, 1, 47, 1, 1, 4, 1, 1, 2, 1, 1, 76, 1, 3, 1, 1, 1, 3, 1, 1, 1, 123, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 199, 1, 1, 2, 7, 1, 2, 1, 1, 2, 1, 1, 322, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 521 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Harvey P. Dale, Rows n = 1..141 of triangle, flattened Paulo Ribenboim, FFF (Favorite Fibonacci Flowers), Fib. Quart. 43 (No. 1, 2005), 3-14. FORMULA T(n, k) = Lucas(g), where g = gcd(n, k), if n/g and k/g are odd; = 2 if n/g or k/g are even and 3|g; = 1 otherwise. MATHEMATICA Flatten[Table[GCD[LucasL[n], LucasL[k]], {n, 20}, {k, n}]] (* Harvey P. Dale, Nov 23 2012 *) PROG (PARI) for(n=1, 10, for(k=1, n, print1(gcd(fibonacci(n+1) + fibonacci(n-1), fibonacci(k+1) + fibonacci(k-1)), ", "))) \\ G. C. Greubel, Dec 17 2017 CROSSREFS Cf. A000032, A111946, A111957. Sequence in context: A176921 A000503 A254864 * A024564 A084795 A030184 Adjacent sequences:  A111953 A111954 A111955 * A111957 A111958 A111959 KEYWORD nonn,tabl AUTHOR N. J. A. Sloane, Nov 28 2005 STATUS approved

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Last modified June 20 04:43 EDT 2021. Contains 345157 sequences. (Running on oeis4.)