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A127750
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Row sums of inverse of number triangle A(n,k) = 1/(2n+1) if k <= n <= 2k, 0 otherwise.
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3
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1, 3, 2, 5, 2, 4, 2, 7, 2, 4, 2, 6, 2, 4, 2, 9, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4, 2, 6, 2, 4, 2, 11, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4, 2, 6, 2, 4, 2, 10, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4, 2, 6, 2, 4, 2, 13, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4, 2, 6, 2, 4, 2, 10, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4, 2, 6, 2, 4, 2, 12, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4
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OFFSET
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0,2
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COMMENTS
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Conjecture: a(n) mod 2 gives Fredholm-Rueppel sequence A036987.
The conjecture is true at least up to n=2048. - Antti Karttunen, Sep 29 2018
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LINKS
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MATHEMATICA
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A[n_, k_] := If[k <= n <= 2k, 1/(2n+1), 0];
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PROG
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(PARI)
up_to = 128;
A127750aux(n, k) = if(k<=n, if(n<=(2*k), 1/(n+n+1), 0), 0);
A127750list(up_to) = { my(m1=matrix(up_to, up_to, n, k, A127750aux(n-1, k-1)), m2 = matsolve(m1, matid(up_to)), v = vector(up_to)); for(n=1, up_to, v[n] = vecsum(m2[n, ])); (v); };
v127750 = A127750list(1+up_to);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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