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.

Showing 1-4 of 4 results.

A326189 Number of distinct nonnegative integers that are reachable from n with some nonempty combination of transitions x -> A032742(x) and x -> A302042(x).

Original entry on oeis.org

0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 4, 1, 3, 1, 3, 4, 2, 1, 4, 2, 2, 4, 3, 1, 3, 1, 5, 4, 2, 2, 4, 1, 2, 3, 4, 1, 5, 1, 3, 7, 2, 1, 5, 2, 3, 4, 3, 1, 5, 4, 4, 6, 2, 1, 4, 1, 2, 6, 6, 3, 5, 1, 3, 6, 3, 1, 5, 1, 2, 4, 3, 2, 4, 1, 5, 8, 2, 1, 6, 4, 2, 4, 4, 1, 8, 4, 3, 9, 2, 3, 6, 1, 3, 6, 4, 1, 5, 1, 4, 7
Offset: 1

Views

Author

Antti Karttunen, Aug 23 2019

Keywords

Comments

Number of distinct numbers > 1 in the directed acyclic graph formed by edge relations x -> A032742(x) and x -> A302042(x), where n is the unique root of the graph.

Examples

			The directed acyclic graph whose unique root is 153 (illustrated below), spans the following seven numbers [1, 5, 17, 25, 51, 75, 153], as A032742(153) = 51, A302042(153) = 75, A032742(51) = 17, A302042(51) = 25, A032742(75) = 25, A302042(75) = 15, A032742(25) = A302042(25) = 5, and A032742(17) = A302042(17) = A032742(5) = A302042(5) = 1. We exclude the root 153 from the count of numbers that are reached, thus a(153) = 6. (Equally, we can include 153, but exclude 1).
.
        153
       /  \
      /    \
     51    75
     / \  /  \
    /   17    \
    \    |    /
     \   1   /
      \     /
       \   /
        25
         |
         5
         |
         1
		

Crossrefs

Programs

  • PARI
    up_to = 65537;
    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; };
    A020639(n) = if(n>1, if(n>n=factor(n, 0)[1, 1], n, factor(n)[1, 1]), 1); \\ From A020639
    A032742(n) = (n/A020639(n));
    v078898 = ordinal_transform(vector(up_to,n,A020639(n)));
    A078898(n) = v078898[n];
    A302042(n) = if((1==n)||isprime(n),1,my(c = A078898(n), p = prime(-1+primepi(A020639(n))+primepi(A020639(c))), d = A078898(c), k=0); while(d, k++; if((1==k)||(A020639(k)>=p),d -= 1)); (k*p));
    A326189aux(n,distvals) = if(1==n,distvals,my(newdistvals=setunion([n],distvals),a=A032742(n), b=A302042(n)); newdistvals = A326189aux(a,newdistvals); if(a==b,newdistvals, A326189aux(b,newdistvals)));
    A326189(n) = length(A326189aux(n,Set([])));

Formula

a(p) = 1 for all primes p.
a(n) >= A326191(n) >= max(A001222(n),A253557(n)) >= min(A001222(n),A253557(n)) >= A326190(n).

A326139 a(n) = gcd(A032742(n), A302042(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 1, 4, 3, 5, 1, 6, 1, 7, 5, 8, 1, 9, 1, 10, 1, 11, 1, 12, 5, 13, 1, 14, 1, 15, 1, 16, 1, 17, 7, 18, 1, 19, 1, 20, 1, 21, 1, 22, 3, 23, 1, 24, 7, 25, 1, 26, 1, 27, 1, 28, 1, 29, 1, 30, 1, 31, 1, 32, 1, 33, 1, 34, 1, 35, 1, 36, 1, 37, 1, 38, 11, 39, 1, 40, 3, 41, 1, 42, 1, 43, 1, 44, 1, 45, 1, 46, 1, 47, 1, 48, 1, 49, 1, 50, 1, 51, 1, 52, 1
Offset: 1

Views

Author

Antti Karttunen, Aug 23 2019

Keywords

Crossrefs

Programs

  • PARI
    up_to = 65537;
    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; };
    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; };
    A020639(n) = if(n>1, if(n>n=factor(n, 0)[1, 1], n, factor(n)[1, 1]), 1); \\ From A020639
    A032742(n) = (n/A020639(n));
    v078898 = ordinal_transform(vector(up_to,n,A020639(n)));
    A078898(n) = v078898[n];
    A302042(n) = if((1==n)||isprime(n),1,my(c = A078898(n), p = prime(-1+primepi(A020639(n))+primepi(A020639(c))), d = A078898(c), k=0); while(d, k++; if((1==k)||(A020639(k)>=p),d -= 1)); (k*p));
    A326139(n) = gcd(A032742(n),A302042(n));

Formula

a(n) = gcd(A032742(n), A302042(n)).

A326190 Length of the shortest path to 1 when starting from x=n and on each iteration step one may always choose either transition x -> A032742(x) or x -> A302042(x).

Original entry on oeis.org

0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 4, 1, 3, 1, 3, 2, 2, 1, 4, 2, 2, 2, 3, 1, 3, 1, 5, 2, 2, 2, 4, 1, 2, 2, 4, 1, 3, 1, 3, 3, 2, 1, 5, 2, 3, 2, 3, 1, 3, 2, 4, 2, 2, 1, 4, 1, 2, 2, 6, 2, 3, 1, 3, 2, 3, 1, 5, 1, 2, 2, 3, 2, 3, 1, 5, 3, 2, 1, 4, 2, 2, 2, 4, 1, 4, 2, 3, 2, 2, 2, 6, 1, 3, 2, 4, 1, 3, 1, 4, 3
Offset: 1

Views

Author

Antti Karttunen, Aug 23 2019

Keywords

Examples

			The directed acyclic graph whose unique root is 153 (illustrated below), spans the following seven numbers [1, 5, 17, 25, 51, 75, 153], as A032742(153) = 51, A302042(153) = 75, A032742(51) = 17, A302042(51) = 25, A032742(75) = 25, A302042(75) = 15, A032742(25) = A302042(25) = 5, and A032742(17) = A302042(17) = A032742(5) = A302042(5) = 1. The length of shortest path(s) from 153 to 1 is 3 (there are actually two shortest paths: 153 -> 51 -> 17 -> 1 and 153 -> 75 -> 17 -> 1), thus a(153) = 3.
.
        153
       /  \
      /    \
     51    75
     / \  /  \
    /   17    \
    \    |    /
     \   1   /
      \     /
       \   /
        25
         |
         5
         |
         1
		

Crossrefs

Programs

  • PARI
    up_to = 65537;
    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; };
    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; };
    A020639(n) = if(n>1, if(n>n=factor(n, 0)[1, 1], n, factor(n)[1, 1]), 1); \\ From A020639
    A032742(n) = (n/A020639(n));
    v078898 = ordinal_transform(vector(up_to,n,A020639(n)));
    A078898(n) = v078898[n];
    A302042(n) = if((1==n)||isprime(n),1,my(c = A078898(n), p = prime(-1+primepi(A020639(n))+primepi(A020639(c))), d = A078898(c), k=0); while(d, k++; if((1==k)||(A020639(k)>=p),d -= 1)); (k*p));
    A326190(n) = if(1==n,0,1+min(A326190(A032742(n)), A326190(A302042(n))));
    \\ Somewhat faster version:
    memo302042 = Map();
    A302042(n) = if((1==n)||isprime(n),1,my(v); if(mapisdefined(memo302042, n, &v), v, my(c = A078898(n), p = prime(-1+primepi(A020639(n))+primepi(A020639(c))), d = A078898(c), k=0); while(d, k++; if((1==k)||(A020639(k)>=p),d -= 1)); v=(k*p); mapput(memo302042,n,v); (v)));
    A326190list(up_to) = { my(v=vector(up_to)); v[1] = 0; for(n=2,up_to, v[n] = 1+min(v[A032742(n)], v[A302042(n)])); (v); };
    v326190 = A326190list(up_to);
    A326190(n) = v326190[n];

Formula

a(1) = 0; for n > 1, a(n) = 1 + min(a(A032742(n)), a(A302042(n))).
a(n) <= min(A001222(n),A253557(n)) <= max(A001222(n),A253557(n)) <= A326191(n) <= A326189(n).

A326191 Length of the longest path to 1 when starting from x=n and on each iteration step one may always choose either transition x -> A032742(x) or x -> A302042(x).

Original entry on oeis.org

0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 4, 1, 3, 1, 3, 3, 2, 1, 4, 2, 2, 3, 3, 1, 3, 1, 5, 3, 2, 2, 4, 1, 2, 2, 4, 1, 4, 1, 3, 4, 2, 1, 5, 2, 3, 3, 3, 1, 4, 3, 4, 4, 2, 1, 4, 1, 2, 4, 6, 2, 4, 1, 3, 4, 3, 1, 5, 1, 2, 3, 3, 2, 3, 1, 5, 4, 2, 1, 5, 3, 2, 3, 4, 1, 5, 3, 3, 5, 2, 2, 6, 1, 3, 4, 4, 1, 4, 1, 4, 4
Offset: 1

Views

Author

Antti Karttunen, Aug 23 2019

Keywords

Examples

			The directed acyclic graph whose unique root is 153 (illustrated below), spans the following seven numbers [1, 5, 17, 25, 51, 75, 153], as A032742(153) = 51, A302042(153) = 75, A032742(51) = 17, A302042(51) = 25, A032742(75) = 25, A302042(75) = 15, A032742(25) = A302042(25) = 5, and A032742(17) = A302042(17) = A032742(5) = A302042(5) = 1. The length of longest path(s) from 153 to 1 is 4 (there are actually two longest paths: 153 -> 51 -> 25 -> 5 -> 1 and 153 -> 75 -> 25 -> 5 -> 1), thus a(153) = 4.
.
        153
       /  \
      /    \
     51    75
     / \  /  \
    /   17    \
    \    |    /
     \   1   /
      \     /
       \   /
        25
         |
         5
         |
         1
		

Crossrefs

Programs

  • PARI
    up_to = 65537;
    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; };
    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; };
    A020639(n) = if(n>1, if(n>n=factor(n, 0)[1, 1], n, factor(n)[1, 1]), 1); \\ From A020639
    A032742(n) = (n/A020639(n));
    v078898 = ordinal_transform(vector(up_to,n,A020639(n)));
    A078898(n) = v078898[n];
    A302042(n) = if((1==n)||isprime(n),1,my(c = A078898(n), p = prime(-1+primepi(A020639(n))+primepi(A020639(c))), d = A078898(c), k=0); while(d, k++; if((1==k)||(A020639(k)>=p),d -= 1)); (k*p));
    A326191(n) = if(1==n,0,1+max(A326191(A032742(n)), A326191(A302042(n))));
    \\ Slightly faster:
    memo302042 = Map();
    A302042(n) = if((1==n)||isprime(n),1,my(v); if(mapisdefined(memo302042, n, &v), v, my(c = A078898(n), p = prime(-1+primepi(A020639(n))+primepi(A020639(c))), d = A078898(c), k=0); while(d, k++; if((1==k)||(A020639(k)>=p),d -= 1)); v=(k*p); mapput(memo302042,n,v); (v)));
    A326191list(up_to) = { my(v=vector(up_to)); v[1] = 0; for(n=2,up_to, v[n] = 1+max(v[A032742(n)], v[A302042(n)])); (v); };
    v326191 = A326191list(up_to);
    A326191(n) = v326191[n];

Formula

a(1) = 0; for n > 1, a(n) = 1 + max(a(A032742(n)), a(A302042(n))).
A326189(n) >= a(n) >= max(A001222(n), A253557(n)) >= min(A001222(n), A253557(n)) >= A326190(n).
Showing 1-4 of 4 results.