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A237450
Triangle read by rows, T(n,k) = !n + (k-1)*(n-1)!, with n>=1, 1<=k<=n; Position of the first n-letter permutation beginning with number k in the list of lexicographically sorted permutations A030299.
2
1, 2, 3, 4, 6, 8, 10, 16, 22, 28, 34, 58, 82, 106, 130, 154, 274, 394, 514, 634, 754, 874, 1594, 2314, 3034, 3754, 4474, 5194, 5914, 10954, 15994, 21034, 26074, 31114, 36154, 41194, 46234, 86554, 126874, 167194, 207514, 247834, 288154, 328474, 368794, 409114, 771994, 1134874, 1497754, 1860634, 2223514, 2586394, 2949274, 3312154, 3675034
OFFSET
1,2
COMMENTS
When organized as a triangular table
1;
2, 3;
4, 6, 8;
10, 16, 22, 28;
34, 58, 82, 106, 130;
...
the k-th term of row n gives the position of the first n-letter permutation beginning with number k among all the lexicographically ordered permutations A030299. Thus the terms give the positions of rows of irregular table A237265 among the rows of A030298.
Note: the notation !n stands for the left factorial, A003422(n).
FORMULA
a(n) = A003422(A002024(n)) + (A002262(n-1)*A000142(A002024(n)-1)).
MATHEMATICA
lf[n_] := lf[n] = (-1)^n n! Subfactorial[-n - 1] - Subfactorial[-1] // FullSimplify;
T[n_, k_] := lf[n] + (k - 1)(n - 1)!;
Table[T[n, k], {n, 1, 10}, {k, 1, n}] // Flatten
PROG
(Scheme) (define (A237450 n) (+ (A003422 (A002024 n)) (* (A002262 (- n 1)) (A000142 (- (A002024 n) 1)))))
CROSSREFS
Left edge: A003422.
Sequence in context: A211856 A066816 A247334 * A165514 A372032 A182417
KEYWORD
nonn,tabl
AUTHOR
Antti Karttunen, Feb 08 2014
STATUS
approved