[seqfan] Re: A026478 [was A026480)

[Don Reble]

>> 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