cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A340028 Number of unlabeled 2-connected graphs with n vertices rooted at a pair of noninterchangeable vertices.

Original entry on oeis.org

0, 1, 1, 7, 55, 655, 11147, 287791, 11787747, 804475261, 94875366649, 19825870580671, 7466490852631207, 5129453728126116131, 6487332587944013948099, 15213161506747424007012971, 66536415576917924594383104139, 545371527333985035460963541248785
Offset: 1

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Author

Andrew Howroyd, Jan 02 2021

Keywords

Crossrefs

Programs

  • PARI
    \\ See A004115 for graphsSeries and A339645 for combinatorial species functions.
    cycleIndexSeries(n)={my(g=graphsSeries(n), gcr=sPoint(g)/g); x*sPoint(sSolve( sLog( gcr/(x*sv(1)) ), gcr ))}
    { my(N=15); Vec(OgfSeries(cycleIndexSeries(N)), -N) }
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