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.

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A331297 Lexicographically earliest infinite sequence such that a(i) = a(j) => A263297(i) = A263297(j) and A325225(i) = A325225(j) for all i, j.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jan 18 2020

Keywords

Comments

Restricted growth sequence transform of the unordered pair [A001222(n), A061395(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; };
    A061395(n) = if(1==n, 0, primepi(vecmax(factor(n)[, 1])));
    Aux331297(n) = { my(a=bigomega(n),b=A061395(n)); [min(a,b),max(a,b)]; };
    Aux331297(n) = Set([bigomega(n),A061395(n)]); \\ Alternatively.
    v331297 = rgs_transform(vector(up_to, n, Aux331297(n)));
    A331297(n) = v331297[n];

Formula

For all i, j:
A331170(i) = A331170(j) => a(i) = a(j),
A331298(i) = A331298(j) => a(i) = a(j),
A331299(i) = A331299(j) => a(i) = a(j),
a(i) = a(j) => A326846(i) = A326846(j).

A331295 Number of values of k, 1 <= k <= n, with f(k) = f(n), where f(n) = [A001222(n), A061395(n)].

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 3, 1, 3, 1, 1, 2, 1, 1, 2, 1, 3, 2, 1, 1, 2, 1, 1, 2, 1, 1, 3, 1, 1, 1, 4, 4, 2, 1, 1, 3, 3, 1, 2, 1, 1, 2, 1, 1, 3, 1, 3, 2, 1, 1, 2, 4, 1, 2, 1, 1, 5, 1, 4, 2, 1, 1, 4, 1, 1, 2, 3, 1, 2, 1, 1, 3, 4, 1, 2, 1, 3, 1, 1, 5, 3, 4, 1, 2, 1, 1, 6
Offset: 1

Views

Author

Antti Karttunen, Jan 19 2020

Keywords

Comments

Ordinal transform of A331298, or equally, of the ordered pair [A001222(n), A061395(n)].

Crossrefs

Programs

  • Mathematica
    f[n_] := f[n] = {PrimeOmega[n], PrimePi[FactorInteger[n]][[-1, 1]]};
    a[n_] := Count[Array[f, n], f[n]];
    Array[a, 105] (* Jean-François Alcover, Jan 10 2022 *)
  • PARI
    up_to = 1001;
    ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
    A061395(n) = if(1==n, 0, primepi(vecmax(factor(n)[, 1])));
    Aux331298(n) = [bigomega(n), A061395(n)];
    v331295 = ordinal_transform(vector(up_to, n, Aux331298(n)));
    A331295(n) = v331295[n];
Showing 1-2 of 2 results.