cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A048622 Difference of maximal and central values of A001222 when applied to {C(n,k)} set.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 2, 1, 2, 1, 0, 0, 2, 1, 0, 0, 0, 0, 0, 1, 3, 2, 1, 1, 3, 2, 1, 0, 2, 1, 2, 1, 1, 0, 0, 0, 2, 2, 1, 0, 1, 1, 3, 2, 3, 2, 0, 0, 2, 0, 0, 0, 4, 3, 4, 3, 2, 2, 3, 3, 5, 4, 3, 2, 2, 1, 2, 1, 3, 2, 1, 1, 2, 1, 0, 0, 1, 1, 3, 2, 1, 0, 0, 0, 3, 2, 2, 2, 4, 2, 2, 2, 3, 2
Offset: 1

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Examples

			n=24: the sums of prime factor exponents when k runs from 0 to 24 are {0,4,4,5,5,7,6,8,6,8,8,9,7,9,8,8,6,8,6,7,5,5,4,4,0}. The central value is 7, the maximal is 9 so a(24)=9-7.
		

Crossrefs

Programs

  • PARI
    a(n) = vecmax(apply(bigomega, vector(n+1, k, binomial(n,k-1)))) - bigomega(binomial(n, n\2)); \\ Michel Marcus, Jun 25 2021

Formula

a(n) = Max_k {A001222(C(n, k))} - A001222(A001405(n)).
a(n) = A048620(n) - A048621(n). - Sean A. Irvine, Jun 24 2021

A048681 Maximum over k of the largest squarefree number dividing a value of binomial(n,k).

Original entry on oeis.org

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

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Examples

			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]
		

Crossrefs

Analogous sequences for A001221, A001222, A000005 are given in A048273, A048275, A048620.

Programs

  • PARI
    a(n) = vecmax(vector(ceil(n\2)+1, k, factorback(factorint(binomial(n,k-1))[, 1]))); \\ Michel Marcus, May 20 2018
Showing 1-2 of 2 results.