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 A277905 Irregular table: Each row n (n >= 0) lists in ascending order all A018819(n) numbers k for which A048675(k) = n. 10
 1, 2, 3, 4, 6, 8, 5, 9, 12, 16, 10, 18, 24, 32, 15, 20, 27, 36, 48, 64, 30, 40, 54, 72, 96, 128, 7, 25, 45, 60, 80, 81, 108, 144, 192, 256, 14, 50, 90, 120, 160, 162, 216, 288, 384, 512, 21, 28, 75, 100, 135, 180, 240, 243, 320, 324, 432, 576, 768, 1024, 42, 56, 150, 200, 270, 360, 480, 486, 640, 648, 864, 1152, 1536, 2048, 35, 63, 84, 112, 125, 225, 300, 400 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Each row beginning with an odd number (rows with even index) is followed by a row of the same length, with the same terms, but multiplied by 2. See also comments in the Formula section of A018819. Note that although the indexing of rows start from zero, the indexing of this sequence starts from 1, with a(1) = 1. LINKS Antti Karttunen, Table of n, a(n) for n = 1..166 FORMULA a(1) = 1; for n > 1, if A277896(a(n-1)) > 0, then a(n) = A277896(a(n-1)), otherwise a(n) = A019565(A277903(n)). [A naive recurrence for a one-dimensional version.] Other identities. For all n >= 1: A048675(a(n)) = A277903(n). EXAMPLE The irregular table begins as:   row terms    0   1;    1   2;    2   3,  4;    3   6,  8;    4   5,  9,  12,  16;    5  10, 18,  24,  32;    6  15, 20,  27,  36,  48,  64;    7  30, 40,  54,  72,  96, 128;    8   7, 25,  45,  60,  80,  81, 108, 144, 192, 256;    9  14, 50,  90, 120, 160, 162, 216, 288, 384, 512;   10  21, 28,  75, 100, 135, 180, 240, 243, 320, 324, 432,  576,  768, 1024;   11  42, 56, 150, 200, 270, 360, 480, 486, 640, 648, 864, 1152, 1536, 2048; ... PROG (Scheme) (definec (A277905 n) (A277905bi (A277903 n) (A277904 n))) (define (A277905bi row col) (let outloop ((k (A019565 row)) (col col)) (if (zero? col) k (let inloop ((j (+ 1 k))) (if (= (A048675 j) row) (outloop j (- col 1)) (inloop (+ 1 j))))))) ;; Very slow implementation. ;; Implementation based on a naive recurrence: (definec (A277905 n) (if (= 1 n) n (let ((maybe_next (A277896 (A277905 (- n 1))))) (if (not (zero? maybe_next)) maybe_next (A019565 (A277903 n)))))) CROSSREFS Cf. A019565 (the left edge, the only terms that are squarefree). Cf. A000079 (the trailing edge). Cf. A048675, A260443, A277886, A277896, A277903, A277904. Sequence in context: A235262 A245704 A260425 * A257802 A225850 A038150 Adjacent sequences:  A277902 A277903 A277904 * A277906 A277907 A277908 KEYWORD nonn,tabf AUTHOR Antti Karttunen, Nov 14 2016 STATUS approved

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Last modified August 3 10:49 EDT 2020. Contains 336198 sequences. (Running on oeis4.)