[seqfan] Re: A066411
Ron Hardin
rhhardin at att.net
Fri Jan 27 19:13:13 CET 2012
I get 1 1 3 5 23 61 143 215 995 2481 5785 12907 29279 64963 144289 158049 which
agrees with the series.
Time in C on a not very fast laptop for the last 3 terms
37h 30m
01h 33m
00h 05m
The method was representing it as a sum of a product of 0..n with binomial
coefficients,
sort the binomial coefficients smallest first,
apply the permutations of 0..15 to these in turn getting a cumulative sum at
each level,
look at each level L whether this set of L elements of 0..15 has been seen
before together with the same sum,
and if so abort further recursion at that level for that case.
I don't know if this implicitly takes into account all the symmetries talked
about.
One that sounds new is converting a n! problem into a 2^n problem, providing the
sums repeat, which is encouraged by taking the smallest coefficients first.
Remembering what has occurred already was subject to cache dumping at the
highest levels first, though I don't think that happened.
rhhardin at mindspring.com
rhhardin at att.net (either)
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