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.

A378605 Lexicographically earliest infinite sequence such that a(i) = a(j) => A001065(i) = A001065(j) and A033630(i) = A033630(j), for all i, j >= 1.

Original entry on oeis.org

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

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Author

Antti Karttunen, Dec 01 2024

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A001065(n), A033630(n)].

Crossrefs

Cf. also A378603.

Programs

  • PARI
    up_to = 100000;
    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; };
    A001065(n) = (sigma(n)-n);
    v033630 = readvec("b033630_to.txt"); \\ Precomputed with A033630(n) = if(!n, 1, my(p=1); fordiv(n, d, p *= (1 + 'x^d)); polcoeff(p, n));
    A033630(n) = v033630[n];
    Aux378605(n) = [A001065(n), A033630(n)];
    v378605 = rgs_transform(vector(up_to, n, Aux378605(n)));
    A378605(n) = v378605[n];