A091291 - OEIS

A091291

Numbers x such that the quotient q=(sigma[x]+sigma[x+1])/sigma[2x+1] is smaller than 0.5, that is (sigma[x]+sigma[x+1])/>2.sigma[2x+1]; sigma=A000203.

1283782, 3445942, 4662157, 5743237, 7770262, 8806297, 8986477, 9572062, 9920137, 10472962, 11356537, 11554042, 12635122, 12870742

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..14.

MATHEMATICA

f[x_] := (DivisorSigma[1, x]+DivisorSigma[1, x+1])/DivisorSigma[1, 2*x+1] Do[s=f[n]; If[ !Greater[s, 0.5], Print[{n, s//N}]]

CROSSREFS

Cf. A000203, A091287-A091290.

Sequence in context: A328256 A118419 A250619 * A205178 A205663 A205952

Adjacent sequences: A091288 A091289 A091290 * A091292 A091293 A091294

KEYWORD

nonn

AUTHOR

Labos Elemer, Feb 16 2004

STATUS

approved