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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A374033 Lexicographically earliest infinite sequence such that a(i) = a(j) => A278226(A373985(i)) = A278226(A373985(j)), for all i, j >= 1.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 3, 3, 1, 1, 1, 1, 3, 2, 1, 2, 2, 2, 4, 1, 1, 1, 1, 1, 2, 2, 2, 5, 1, 2, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 3, 1, 1, 2, 6, 7, 3, 2, 1, 8, 1, 2, 1, 2, 6, 1, 1, 1, 2, 1, 1, 4, 1, 2, 1, 1, 6, 1, 1, 1, 7, 2, 1, 9, 2, 2, 3, 2, 1, 2, 6, 1, 3, 2, 2, 5, 1, 1, 10, 5, 1, 1, 1, 2, 1
Offset: 1

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Author

Antti Karttunen, Jun 27 2024

Keywords

Comments

Restricted growth sequence transform of A278226(A373985(n)).
For all i, j >= 1:
A305800(i) = A305800(j) => a(i) = a(j) => A373989(i) = A373989(j).

Crossrefs

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; };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };
    A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
    A278226(n) = A046523(A276086(n));
    A373985(n) = { my(f=factor(n),m=1,s=0); for(i=1, #f~, my(x=prod(i=1,primepi(f[i, 1]),prime(i))); s += f[i, 2]*x; m *= x^f[i, 2]); gcd(m,s); };
    v374033 = rgs_transform(vector(up_to, n, A278226(A373985(n))));
    A374033(n) = v374033[n];

A374034 a(n) = A276150(gcd(A276085(n), A328768(n))), where A276150 is the digit sum in primorial base, A276085 is the primorial base log-function, and A328768 is the first primorial based variant of arithmetic derivative.

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 3, 2, 1, 2, 1, 1, 1, 2, 3, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 4, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 2, 4, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2, 1, 1, 6, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3
Offset: 1

Views

Author

Antti Karttunen, Jun 27 2024

Keywords

Crossrefs

Programs

  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*A002110(primepi(f[k, 1])-1)); };
    A276150(n) = { my(s=0, p=2, d); while(n, d = (n%p); s += d; n = (n-d)/p; p = nextprime(1+p)); (s); };
    A328768(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]*A002110(primepi(f[i,1])-1)/f[i, 1]));
    A374034(n) = A276150(gcd(A276085(n), A328768(n)));

Formula

a(n) = A276150(A374031(n)).
Apparently, a(n) <= A328771(n) for all n >= 1.
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