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.

A297169 Restricted growth sequence transform of a(1) = -1, a(n) = A297168(n) for n > 1.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 4, 5, 6, 2, 7, 2, 8, 9, 7, 2, 8, 2, 10, 11, 12, 2, 13, 14, 15, 9, 16, 2, 12, 2, 13, 17, 18, 19, 16, 2, 20, 21, 22, 2, 23, 2, 24, 25, 26, 2, 27, 28, 12, 29, 30, 2, 31, 32, 33, 34, 35, 2, 24, 2, 36, 37, 27, 38, 39, 2, 40, 41, 15, 2, 33, 2, 42, 17, 43, 44, 45, 2, 46, 25, 47, 2, 48, 49, 50, 51, 52, 2, 53, 54, 55, 56, 57, 58, 59, 2, 15, 60, 24
Offset: 1

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Author

Antti Karttunen, Feb 27 2018

Keywords

Comments

For all i, j: A300827(i) = A300827(j) => a(i) = a(j). - Antti Karttunen, Mar 13 2018

Crossrefs

Programs

  • PARI
    allocatemem(2^30);
    up_to = 8192;
    rgs_transform(invec) = { my(occurrences = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(occurrences,invec[i]), my(pp = mapget(occurrences, invec[i])); outvec[i] = outvec[pp] , mapput(occurrences,invec[i],i); outvec[i] = u; u++ )); outvec; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A061395(n) = if(1==n, 0, primepi(vecmax(factor(n)[, 1])));
    A297167(n) = if(1==n, 0, (A061395(n) + (bigomega(n)-omega(n)) - 1));
    A297112(n) = if(1==n,0,2^A297167(n));
    A297168v1(n) = if(1==n,-1,sumdiv(n,d,(dA297112(d)));
    write_to_bfile(1,rgs_transform(vector(up_to,n,A297168v1(n))),"b297169.txt");
    \\ (More efficient PARI program) - Antti Karttunen, Mar 13 2018