[seqfan] Re: two dumb questions
Brad Klee
bradklee at gmail.com
Sat Jul 22 04:14:24 CEST 2017
Hi Peter,
Yes, it looks like your triangle has at least one permutation error in row
six.
http://oeis.org/A054521
http://oeis.org/A215200
Also, the definition of A054521 is more standard and easier to understand
than what you propose for Axxxxxx.
Thanks,
Brad
On Fri, Jul 21, 2017 at 8:43 PM, Peter Lawrence <peterl95124 at sbcglobal.net>
wrote:
>
> A051731: characteristic triangle of divisors of n
>
> A000005: = number of divisors of n = row sums of A051731
>
> 1. How is A051731 different from Redheffer matrix A143104,
> which seems to have same FORMULA definition ?
> a(i,j) = 1 if j=1 or j|i; 0 otherwise.
>
>
>
>
>
> Axxxxxx: characteristic triangle of numbers with gcd( I, j ) = 1
>
> A000010 = number of relative-primes of n = row sums of Axxxxxx
>
>
> a(i,j) = 1 if gcd(j,i) = 1; 0 otherwise.
>
> 1: 1, 1
> 2: 1, 0, 1
> 3: 1, 1, 0, 2
> 4: 1, 0, 1, 0, 2
> 5: 1, 1, 1, 1, 0, 4
> 6: 1, 0, 0, 1, 0, 0, 2
> 7: 1, 1, 1, 1, 1, 1, 0, 6
> 8: 1, 0, 1, 0, 1, 0, 1, 0, 4
> 9: 1, 1, 0, 1, 1, 0, 1, 1, 0, 6
> 10: 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 4
> 11: 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 10
> 12: 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 4
> 13: 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 12
> 14: 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 6
> 15: 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 8
> 16: 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 8
>
>
> 2. I suspect I computed this triangle incorrectly, because I can’t find
> it in the OEIS _?_
>
>
>
> Peter Lawrence.
>
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