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 A286101 Square array A(n,k) read by antidiagonals: A(n,k) = T(gcd(n,k), lcm(n,k)), where T(n,k) is sequence A000027 considered as a two-dimensional table. 8
 1, 2, 2, 4, 5, 4, 7, 16, 16, 7, 11, 12, 13, 12, 11, 16, 46, 67, 67, 46, 16, 22, 23, 106, 25, 106, 23, 22, 29, 92, 31, 191, 191, 31, 92, 29, 37, 38, 211, 80, 41, 80, 211, 38, 37, 46, 154, 277, 379, 436, 436, 379, 277, 154, 46, 56, 57, 58, 59, 596, 61, 596, 59, 58, 57, 56, 67, 232, 436, 631, 781, 862, 862, 781, 631, 436, 232, 67, 79, 80, 529, 212, 991, 302, 85, 302, 991, 212, 529, 80, 79 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The array is read by descending antidiagonals as A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), etc. LINKS MathWorld, Pairing Function FORMULA A(n,k) = T(gcd(n,k), lcm(n,k)), where T(n,k) is sequence A000027 considered as a two-dimensional table, that is, as a pairing function from N x N to N. A(n,k) = A(k,n), or equivalently, a(A038722(n)) = a(n). [Array is symmetric.] EXAMPLE The top left 12 X 12 corner of the array:    1,   2,   4,   7,   11,   16,   22,   29,   37,   46,   56,   67    2,   5,  16,  12,   46,   23,   92,   38,  154,   57,  232,   80    4,  16,  13,  67,  106,   31,  211,  277,   58,  436,  529,   94    7,  12,  67,  25,  191,   80,  379,   59,  631,  212,  947,  109   11,  46, 106, 191,   41,  436,  596,  781,  991,   96, 1486, 1771   16,  23,  31,  80,  436,   61,  862,  302,  193,  467, 2146,  142   22,  92, 211, 379,  596,  862,   85, 1541, 1954, 2416, 2927, 3487   29,  38, 277,  59,  781,  302, 1541,  113, 2557,  822, 3829,  355   37, 154,  58, 631,  991,  193, 1954, 2557,  145, 4006, 4852,  706   46,  57, 436, 212,   96,  467, 2416,  822, 4006,  181, 5996, 1832   56, 232, 529, 947, 1486, 2146, 2927, 3829, 4852, 5996,  221, 8647   67,  80,  94, 109, 1771,  142, 3487,  355,  706, 1832, 8647,  265 PROG (Scheme) (define (A286101 n) (A286101bi (A002260 n) (A004736 n))) (define (A286101bi row col) (A000027bi (gcd row col) (lcm row col))) (define (A000027bi row col) (* (/ 1 2) (+ (expt (+ row col) 2) (- row) (- (* 3 col)) 2))) CROSSREFS Cf. A000124 (row 1 and column 1), A001844 (main diagonal). Cf. A000027, A003989, A003990, A003991, A038722, A285722, A285732, A286098, A286099, A286102, A285724. Sequence in context: A136099 A210597 A252836 * A072454 A115216 A208637 Adjacent sequences:  A286098 A286099 A286100 * A286102 A286103 A286104 KEYWORD nonn,tabl AUTHOR Antti Karttunen, May 03 2017 STATUS approved

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Last modified June 12 09:24 EDT 2021. Contains 344946 sequences. (Running on oeis4.)