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.

A366294 Lexicographically earliest infinite sequence such that a(i) = a(j) => A326042(i) = A326042(j) for all i, j >= 1, where A326042(n) = A064989(sigma(A003961(n))).

Original entry on oeis.org

1, 1, 2, 3, 1, 2, 2, 4, 5, 1, 6, 7, 8, 2, 2, 9, 4, 5, 2, 3, 8, 6, 10, 10, 11, 8, 7, 7, 1, 2, 12, 13, 14, 4, 2, 15, 14, 2, 16, 4, 17, 8, 2, 13, 5, 10, 16, 18, 19, 11, 10, 20, 10, 7, 6, 10, 8, 1, 5, 7, 21, 12, 22, 23, 8, 14, 8, 24, 25, 2, 26, 27, 4, 14, 28, 7, 14, 16, 14, 9, 29, 17, 25, 20, 4, 2, 2, 30, 31, 5, 16, 32
Offset: 1

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Author

Antti Karttunen, Oct 07 2023

Keywords

Comments

Restricted growth sequence transform of A326042.

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
    A064989(n) = { my(f=factor(n>>valuation(n,2))); for(i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f); };
    A326042(n) = A064989(sigma(A003961(n)));
    v366294  = rgs_transform(vector(up_to,n,A326042(n)));
    A366294(n) = v366294[n];