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A080396
Largest squarefree numbers dividing the binomial coefficients C(n,k) read by row, 0<=k<=n. Squarefree kernel of Pascal triangle.
3
1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 2, 6, 2, 1, 1, 5, 10, 10, 5, 1, 1, 6, 15, 10, 15, 6, 1, 1, 7, 21, 35, 35, 21, 7, 1, 1, 2, 14, 14, 70, 14, 14, 2, 1, 1, 3, 6, 42, 42, 42, 42, 6, 3, 1, 1, 10, 15, 30, 210, 42, 210, 30, 15, 10, 1, 1, 11, 55, 165, 330, 462, 462, 330, 165, 55, 11, 1, 1, 6, 66
OFFSET
0,5
FORMULA
a(n) = A007947(A007318(n)).
EXAMPLE
Triangle begins:
1,
1,1,
1,2,1,
1,3,3,1,
1,2,6,2,1,
1,5,10,10,5,1,
1,6,15,10,15,6,1, ...
PROG
(PARI) T(n, k) = factorback(factorint(binomial(n, k))[, 1]);
tabl(nn) = for(n=0, nn, for (k=0, n, print1(T(n, k), ", ")); print); \\ Michel Marcus, May 20 2018
CROSSREFS
Sequence in context: A307239 A204087 A080381 * A155582 A169946 A160832
KEYWORD
nonn,tabl
AUTHOR
Labos Elemer, Mar 19 2003
STATUS
approved