[seqfan] Re: More first differences -- with composites (corrected) (2)

Eric Angelini Eric.Angelini at kntv.be
Thu Jun 20 15:17:06 CEST 2013


... or better, try to subtract first, then add...
(sorry -- this is obvious for me, not at all for 
the "normal" reader)
best,
É.

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... correction hereunder, of course:

> S starts with a(1)=1, then we always try to add

should be:

> S starts with a(1)=1, then we always try to add
  or subtract (...)

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Hello SeqFans,
is S the "equivalent" of http://oeis.org/A109888
if we drop the "strictly increasing" constraint?

S=1,9,15,25,21,33,49,35,55,...

S starts with a(1)=1, then we always try to add
to a(n) the smallest composite:
- not yet in S;
- not yet in the first differences of S;
- not producing a prime.

S =  1, 9, 15, 25, 21, 33, 49, 35, 55,...
diff:  8  6  10   4  12  16  14  20

As usual, S, merged with its first differences,
is conjectured to be a permutation of the non-primes.
Best,
É.




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