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A self-generating sequence: there are a(n) (k+1)'s between successive k's, where k=4.
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%I #5 May 20 2014 14:54:16

%S 4,5,5,5,5,4,5,5,5,5,5,4,5,5,5,5,5,4,5,5,5,5,5,4,5,5,5,5,5,4,5,5,5,5,

%T 4,5,5,5,5,5,4,5,5,5,5,5,4,5,5,5,5,5,4,5,5,5,5,5,4,5,5,5,5,5,4,5,5,5,

%U 5,4,5,5,5,5,5,4,5,5,5,5

%N A self-generating sequence: there are a(n) (k+1)'s between successive k's, where k=4.

%p f := proc(n,k) floor(n*(k+sqrt(k^2+4*k))/2)-floor((n-1)*(k+sqrt(k^2+4*k))/2); end; (with k=4)

%Y Cf. A001468, A007538.

%K nonn

%O 1,1

%A _Jonas Wallgren_