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A198788
Array T(k,n) read by descending antidiagonals: Last survivor positions in Josephus problem for n numbers and a count of k, n >= 1, k >= 1.
4
1, 2, 1, 3, 1, 1, 4, 3, 2, 1, 5, 1, 2, 1, 1, 6, 3, 1, 2, 2, 1, 7, 5, 4, 2, 1, 1, 1, 8, 7, 1, 1, 2, 1, 2, 1, 9, 1, 4, 5, 2, 3, 3, 1, 1, 10, 3, 7, 2, 1, 4, 2, 3, 2, 1, 11, 5, 1, 6, 6, 4, 4, 3, 2, 1, 1, 12, 7, 4, 1, 3, 3, 5, 1, 3, 2, 2, 1, 13, 9, 7, 5, 8, 1, 5, 3
OFFSET
1,2
COMMENTS
Arrange 1, 2, 3, ... n clockwise in a circle. Starting the count at 1, delete every k-th integer clockwise until only one remains, which is T(k,n).
The main diagonal of the array (1, 1, 2, 2, 2, 4, 5, 4, ...) is A007495.
Consecutive columns down to the main diagonal (1, 2, 1, 3, 3, 2, 4, 1, 1, 2, ...) is A032434.
Period lengths of columns (1, 2, 6, 12, 60, 60, 420, 840, ...) is A003418.
FORMULA
T(k,1) = 1;
for n > 1: T(k,n) = ((T(k,n-1) + k - 1) mod n) + 1.
EXAMPLE
.k\n 1 2 3 4 5 6 7 8 9 10
----------------------------------
.1 | 1 2 3 4 5 6 7 8 9 10 A000027
.2 | 1 1 3 1 3 5 7 1 3 5 A006257
.3 | 1 2 2 1 4 1 4 7 1 4 A054995
.4 | 1 1 2 2 1 5 2 6 1 5 A088333
.5 | 1 2 1 2 2 1 6 3 8 3 A181281
.6 | 1 1 1 3 4 4 3 1 7 3
.7 | 1 2 3 2 4 5 5 4 2 9 A178853
.8 | 1 1 3 3 1 3 4 4 3 1 A109630
.9 | 1 2 2 3 2 5 7 8 8 7
10 | 1 1 2 4 4 2 5 7 8 8
CROSSREFS
Cf. A000027 (k = 1), A006257 (k = 2), A054995 (k = 3), A088333 (k = 4), A181281 (k = 5), A178853 (k = 7), A109630 (k = 8).
Cf. A003418, A007495 (main diagonal), A032434, A198789, A198790.
Sequence in context: A122610 A011973 A115139 * A112543 A099478 A133913
KEYWORD
nonn,easy,tabl
AUTHOR
STATUS
approved