[seqfan] Re: A026478 [was A026480)
djr at nk.ca
Thu Sep 22 18:38:06 CEST 2016
>> A026480: "a(n) = least positive integer > a(n-1) and not
>> a(i)*a(j)*a(k) for 1<=i<=j<=k<=n."
>> This doesn't make any sense to me. Since a(1) = 1, any a(n) =
>> a(i)*a(j)*a(k) for the case i=j=1, k=n.
>> What is this sequence supposed to be?
There are six such sequences, defined by the first three terms
and whether representation repetitions are allowed.
A026477 1 <= i < j < k < n 1,2,3
A026478 1 <= i <= j <= k < n 1,2,3
A026479 1 <= i < j < k <= n 1,2,4
A026480 1 <= i <= j <= k <= n 1,2,4
A026481 1 <= i < j < k <= n 1,3,4
A026482 1 <= i <= j <= k < n 1,3,4
But each "<= n" should be "< n".
> But A026478 itself seems to be in a bit of a mess...
> ...caused some recent "corrections", such as removing 128.
Yes, 128 should be in A026478.
Don Reble djr at nk.ca
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