|
|
A250485
|
|
Regular triangle array: number of [0-r]-covering hierarchies with thickness = e.
|
|
0
|
|
|
1, 1, 2, 1, 6, 4, 1, 14, 22, 8, 1, 30, 86, 64, 16, 1, 62, 294, 346, 168, 32, 1, 126, 938, 1594, 1140, 416, 64, 1, 254, 2874, 6746, 6422, 3376, 992, 128, 1, 510, 8586, 27098, 32758, 22192, 9344, 2304, 256, 1, 1022, 25234, 105090, 157326, 129914, 69840, 24672, 5248, 512
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
G. Kreweras, Sur les hiérarchies de segments, Cahiers du Bureau Universitaire de Recherche Opérationnelle, Institut de Statistique, Université de Paris, #20 (1973), p. 25-27.
G. Kreweras, Sur les hiérarchies de segments, Cahiers du Bureau Universitaire de Recherche Opérationnelle, Institut de Statistique, Université de Paris, #20 (1973). (Annotated scanned copy)
|
|
FORMULA
|
|
|
EXAMPLE
|
Triangle starts:
1;
1, 2;
1, 6, 4;
1, 14, 22, 8;
1, 30, 86, 64, 16;
1, 62, 294, 346, 168, 32;
...
|
|
PROG
|
(PARI) tabl(nn) = {v = vector(nn); v[1] = 1; for (n=2, nn, v[n] = 1 + t*v[n-1]^2/(1 - t*v[n-1]); ); pv = vector(nn, n, v[n]+O(t^(nn+1))); m = matrix(nn, nn, n, k, polcoeff(pv[n], k-1, t)); m = m ~; for (n= 2, nn, for (k=2, n, print1(m[n, k]-m[n, k-1], ", "); ); print(); ); }
|
|
CROSSREFS
|
|
|
KEYWORD
|
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|