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.

A295886 Filter-sequence combining A003557(n) and A023900(n).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 21, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 34, 38, 39, 13, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 54, 71, 72, 73, 67, 74, 75, 76, 52, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 73
Offset: 1

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Author

Antti Karttunen, Dec 03 2017

Keywords

Comments

For all i, j: a(i) = a(j) => A295887(i) = A295887(j).

Crossrefs

Programs

  • PARI
    allocatemem(2^30);
    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; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A003557(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 2] = max(0,f[i, 2]-1)); factorback(f); };
    A023900(n) = sumdivmult(n, d, d*moebius(d)); \\ This function from Charles R Greathouse IV, Sep 09 2014
    v295876 = rgs_transform(vector(up_to,n,A023900(n)))
    A295876(n) = v295876[n];
    Anotsubmitted6(n) = (1/2)*(2 + ((A003557(n)+A295876(n))^2) - A003557(n) - 3*A295876(n));
    write_to_bfile(1,rgs_transform(vector(up_to,n,Anotsubmitted6(n))),"b295886.txt");

Formula

Restricted growth sequence transform of sequence a(n) = (1/2)*(2 + ((A003557(n) + A295876(n))^2) - A003557(n) - 3*A295876(n)).