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A038871
Triangle read by rows: T(n,k) = number of orbits of order k under doubling map which remain in a semicircle, with k dividing n.
2
0, 1, 1, 3, 1, 5, 7, 1, 5, 11, 15, 1, 9, 21, 27, 31, 1, 9, 21, 43, 55, 63, 1, 17, 37, 85, 91, 119, 127, 1, 17, 73, 85, 171, 219, 239, 255, 1, 33, 73, 165, 341, 363, 439, 495, 511, 1, 33, 137, 293, 341, 683, 731, 887, 991, 1023, 1, 65, 273, 585, 661, 1365, 1387
OFFSET
1,4
FORMULA
Apparently T(n, k) = Sum_{j=0..n-1} 2^floor(n*j/k), for 0 <= k <= n - 2 with T(1,0)=0. - Sean A. Irvine, Feb 16 2021
EXAMPLE
From Sean A. Irvine, Feb 16 2021: (Start)
Triangle begins:
0;
1;
1, 3;
1, 5, 7;
1, 5, 11, 15;
1, 9, 21, 27, 31;
1, 9, 21, 43, 55, 63;
1, 17, 37, 85, 91, 119, 127;
1, 17, 73, 85, 171, 219, 239, 255;
1, 33, 73, 165, 341, 363, 439, 495, 511;
...
(End)
CROSSREFS
Cf. A038870.
Sequence in context: A278032 A016600 A130418 * A209819 A193648 A221881
KEYWORD
nonn,tabf,easy
AUTHOR
Francois Maurel (maurel(AT)sequoia.ens.fr)
STATUS
approved