David Wilson wrote:
<<
I took a look at Ulam(1,2), the Ulam sequence starting with (1, 2) and
including every subsequent number which is a unique sum of distinct
earlier terms. This is Sloane's A002858.
>>
Actually A002858 is described in EIS as
"Ulam numbers: next is uniquely the sum of 2 earlier terms"
It's listed in EIS as beginning
1,2,3,4,6,8,11,13,..., (least such)
but one could get a whole nother sequence via
1,2,3,5,8,13,21,34,..., (largest such)
or
1,2,3,5,4,9,8,17,..., (largest alternating with least)
for instance.
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To well-define A002858 perhaps one should define it as
"[Sequence beginning with 1,2 whose] next term is *the least* unique sum of 2 previous terms"
QUESTION: If "2 previous terms" were replaced with "any number of previous terms" in this definition, would it be a different sequence?
--Dan A.