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A048681
Maximum over k of the largest squarefree number dividing a value of binomial(n,k).
0
1, 2, 3, 6, 10, 15, 35, 70, 42, 210, 462, 462, 858, 3003, 5005, 4290, 24310, 24310, 92378, 125970, 293930, 646646, 1352078, 1352078, 817190, 5311735, 2897310, 13123110, 34597290, 17298645, 100180065, 200360130, 129644790, 2203961430
OFFSET
1,2
EXAMPLE
For n=10, the squarefree kernels of binomial(n,k) are {1, 10, 15, 30, 210, 42, 210, 30, 15, 10, 1}, so the maximal largest squarefree divisor is that of binomial(10,4)=210: it is 210, so a(10)=210. (It is not equal to the largest squarefree number dividing binomial(10,5)=252, which is A048633(10)=42.) [edited by Jon E. Schoenfield, May 19 2018]
PROG
(PARI) a(n) = vecmax(vector(ceil(n\2)+1, k, factorback(factorint(binomial(n, k-1))[, 1]))); \\ Michel Marcus, May 20 2018
CROSSREFS
Analogous sequences for A001221, A001222, A000005 are given in A048273, A048275, A048620.
Sequence in context: A370819 A055789 A238891 * A375972 A051891 A108062
KEYWORD
nonn
AUTHOR
STATUS
approved