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.

A324346 Lexicographically earliest positive sequence such that a(i) = a(j) => A005811(i) = A005811(j) and A324055(i) = A324055(j), for all i, j >= 0.

Original entry on oeis.org

1, 2, 3, 2, 4, 5, 6, 2, 7, 8, 9, 10, 11, 12, 13, 2, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 21, 22, 2, 27, 28, 29, 5, 30, 19, 18, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 2, 55, 56, 18, 15, 57, 19, 58, 59, 60, 61, 62, 63, 64, 65, 32, 66, 67, 68, 69, 63, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81
Offset: 0

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Author

Antti Karttunen, Feb 24 2019

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A005811(n), A324055(n)].

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; };
    A005811(n) = hammingweight(bitxor(n, n>>1)); \\ From A005811
    A324055(n) = { my(m1=2,m2=1,p=2,mp=p*p); while(n, if(!(n%2), p=nextprime(1+p); mp = p*p, m1 *= p; if(3==(n%4),mp *= p,m2 *= (mp-1)/(p-1))); n>>=1); (m1-m2); };
    Aux324346(n) = [A005811(n), A324055(n)];
    v324346 = rgs_transform(vector(1+up_to,n,Aux324346(n-1)));
    A324346(n) = v324346[1+n];

Formula

For all n >= 1, a((2^n)-1) = 2.