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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A227196 a(n) = first i >= 1 for which the Kronecker symbol K(i,n) is not +1 (i.e., is either 0 or -1), 0 if no such i exists.

Original entry on oeis.org

0, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 5, 2, 5, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 5, 2, 7, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 7, 2, 5, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 3
Offset: 1

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Author

Antti Karttunen, Jul 06 2013

Keywords

Comments

a(1) = 0, because K(i,1) is 1 for all i. After that, A112046 interleaved with A007395.
All terms beyond a(1) = 0 are prime numbers. Heuristically a(n) is 2 3/4 of the time, 3 1/6 of the time, 5 1/20 of the time, 7 2/105 of the time, etc. The average value is 2.5738775742512.... - Charles R Greathouse IV, Jan 30 2018

Crossrefs

Bisections: A112046 (for odd terms from 3 onward), A007395 (all even terms).

Programs

  • PARI
    a(n) = for(k=1,n,if(kronecker(k,n)<1, return(k)))
    for(n=1,120, print1(a(n),", "))

Formula

A227195(n) = a(n)-1 for all n>=2.
a(2n+1) = A112046(n) for all n>0. - A.H.M. Smeets Jan 29 2018
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