A229718 - OEIS

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A229718

Number of arrays of length 2 that are sums of n consecutive elements of length 2+n-1 permutations of 0..2+n-2, and no two consecutive rises or falls in the latter permutation.

%I #8 Apr 28 2021 01:25:00

%S 2,4,8,18,26,40,52,70,86,108,128,154,178,208

%N Number of arrays of length 2 that are sums of n consecutive elements of length 2+n-1 permutations of 0..2+n-2, and no two consecutive rises or falls in the latter permutation.

%C Row 2 of A229717.

%F Empirical: a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4) for n > 5.

%e Some solutions for n=4:

%e 10 6 9 7 9 8 8 8 6 8 7 6 7 10 10 7

%e 7 9 8 8 6 10 7 6 8 9 10 7 9 8 9 6

%K nonn,more

%O 1,1

%A _R. H. Hardin_, Sep 27 2013

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Last modified December 7 15:42 EST 2023. Contains 367658 sequences. (Running on oeis4.)