[seqfan] A (not triangular) array inspired by A083197
Eric Angelini
Eric.Angelini at kntv.be
Mon Apr 8 15:14:23 CEST 2013
Hello SeqFans,
http://oeis.org/A083197
... has given me the idea of a variation. Here is A083197:
> Triangular array, read by rows, where
if n is odd the n-th row consists of n least unused non-primes, while
if n is even the n-th row consists of the n least unused primes.
Triangle begins:
1
2 3
4 6 8
5 7 11 13
9 10 12 14 15
17 19 23 29 31 37
etc.
-----------------
... In this variation the size of each row is given by the successive
integers of the sequence itself, not by n. Thus the array would begin:
row size
1 1 (non-prime)
2 3 2 (primes)
4 6 8 3 (non-primes)
5 7 11 13 4 (primes)
9 10 12 14 15 16 6 (non-primes)
17 19 23 29 31 37 41 43 8 (primes)
18 20 21 22 24 5 (non-primes)
47 51 53 59 61 67 71 7 (primes)
25 26 27 28 30 32 33 34 35 36 38 11 (non-primes)
...
As A083197, this new seq is of course a permutation of the natural numbers.
Best,
É.
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