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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A351040 Lexicographically earliest infinite sequence such that a(i) = a(j) => A336158(i) = A336158(j), A206787(i) = A206787(j) and A336651(i) = A336651(j) for all i, j >= 1.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jan 31 2022

Keywords

Comments

Restricted growth sequence transform of the ordered triplet [A336158(n), A206787(n), A336651(n)].
For all i, j >= 1:
A003602(i) = A003602(j) => a(i) = a(j),
a(i) = a(j) => A336390(i) = A336390(j) => A336391(i) = A336391(j),
a(i) = a(j) => A347374(i) = A347374(j),
a(i) = a(j) => A351036(i) = A351036(j) => A113415(i) = A113415(j),
a(i) = a(j) => A351461(i) = A351461(j).
From Antti Karttunen, Nov 23 2023: (Start)
Conjectured to be equal to the lexicographically earliest infinite sequence such that b(i) = b(j) => A000593(i) = A000593(j), A336158(i) = A336158(j) and A336467(i) = A336467(j), for all i, j >= 1 (this was the original definition). In any case it holds that a(i) = a(j) => b(i) = b(j) for all i, j >= 1. See comment in A351461.
(End)

Crossrefs

Differs from A347374 for the first time at n=103, where a(103) = 48, while A347374(103) = 30.
Differs from A351035 for the first time at n=175, where a(175) = 80, while A351035(175) = 78.
Differs from A351036 for the first time at n=637, where a(637) = 272, while A351036(637) = 261.

Programs

  • PARI
    up_to = 65539;
    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; };
    A000265(n) = (n>>valuation(n,2));
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };
    A336158(n) = A046523(A000265(n));
    A206787(n) = sumdiv(n, d, d*(d % 2)*issquarefree(d));
    A336651(n) = { my(f=factor(n)); prod(i=1, #f~, if(2==f[i,1],1,f[i,1]^(f[i,2]-1))); };
    Aux351040(n) = [A336158(n), A206787(n), A336651(n)];
    v351040 = rgs_transform(vector(up_to, n, Aux351040(n)));
    A351040(n) = v351040[n];

Extensions

Original definition moved to the comment section and replaced with a definition that is at least as encompassing, and conjectured to be equal to the original one. - Antti Karttunen, Nov 23 2023

A365388 Lexicographically earliest infinite sequence such that a(i) = a(j) => A334867(i) = A334867(i) and A365386(j) = A365386(j) for all i, j >= 1.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Sep 07 2023

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A334867(n), A365386(n)], or equally, of the quadruplet [A329697(n), A334204(n), A331410(n), A365385(n)].
For all i, j:
A003602(i) = A003602(j) => a(i) = a(j),
a(i) = a(j) => A334867(i) = A334867(j),
a(i) = a(j) => A335880(i) = A335880(j),
a(i) = a(j) => A365386(i) = A365386(j).

Crossrefs

Differs from A003602 and A351090 for the first time at n=99, where a(99) = 41, while A003602(99) = A351090(99) = 50.

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; };
    A163511(n) = if(!n, 1, my(p=2, t=1); while(n>1, if(!(n%2), (t*=p), p=nextprime(1+p)); n >>= 1); (t*p));
    A329697(n) = if(!bitand(n,n-1),0,1+A329697(n-(n/vecmax(factor(n)[, 1]))));
    A334204(n) = A329697(A163511(n));
    A331410(n) = if(!bitand(n,n-1),0,1+A331410(n+(n/vecmax(factor(n)[, 1]))));
    A365385(n) = A331410(A163511(n));
    A365388aux(n) = [A329697(n),A334204(n),A331410(n),A365385(n)];
    v365388 = rgs_transform(vector(up_to,n,A365388aux(n)));
    A365388(n) = v365388[n];

A309797 Lexicographically earliest sequence of positive integers such that for any n > 0 there are no more than a(n) numbers k > 0 such that a(n + k) = a(n + 2*k).

Original entry on oeis.org

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

Views

Author

Rémy Sigrist, Nov 11 2019

Keywords

Comments

The sequence is well defined as we can always extend the sequence with a number that has not yet appeared.
The number 1 appears infinitely many times in the sequence:
- by contradiction: suppose that m is the index of the last occurrence of 1 in the sequence,
- there is no n > 0 such that n + k = m and n + 2*k = 2*m (with k > 0),
- so we can choose a(2*m) = 1, QED.
This sequence has connections with A003602:
- here we have up to a(n) numbers k such that a(n+k) = a(n+2*k), there we have no such numbers,
- for any v >= 0, let f_v be the lexicographically earliest sequence of positive integers such that there are no more than v numbers k such that f_v(n + k) = f_v(n + 2*k),
- then f_v corresponds to A003602 where all but the first term have been repeated 2*v+1 times.

Examples

			The first terms, alongside the corresponding k's, are:
  n   a(n)  k's
  --  ----  ----------
   1     1  {1}
   2     1  {1}
   3     1  {2}
   4     1  {1}
   5     2  {1, 3}
   6     2  {2, 14}
   7     2  {1, 2}
   8     1  {1}
   9     1  {1}
  10     1  {4}
  11     1  {1}
  12     3  {2, 3, 68}
  13     3  {1, 4, 22}
  14     2  {1, 2}
		

Crossrefs

Cf. A003602, A329268 (positions of 1).

Programs

  • PARI
    See Links section.

Formula

a(n) >= #{ k>0 such that a(n+k) = a(n+2*k) }.

A336394 Lexicographically earliest infinite sequence such that a(i) = a(j) => A278222(i) = A278222(j) and A331410(i) = A331410(j), for all i, j >= 1.

Original entry on oeis.org

1, 1, 2, 1, 3, 2, 4, 1, 3, 3, 5, 2, 5, 4, 6, 1, 7, 3, 8, 3, 9, 5, 10, 2, 11, 5, 12, 4, 13, 6, 14, 1, 7, 7, 8, 3, 15, 8, 16, 3, 17, 9, 18, 5, 19, 10, 20, 2, 5, 11, 21, 5, 19, 12, 22, 4, 13, 13, 22, 6, 20, 14, 23, 1, 24, 7, 11, 7, 17, 8, 16, 3, 25, 15, 26, 8, 18, 16, 27, 3, 15, 17, 18, 9, 28, 18, 29, 5, 26, 19, 30, 10, 31, 20, 32, 2, 8, 5, 21, 11
Offset: 1

Views

Author

Antti Karttunen, Aug 10 2020

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A278222(n), A331410(n)].
For all i, j: A324400(i) = A324400(j) => A003602(i) = A003602(j) => a(i) = a(j).

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; };
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A278222(n) = A046523(A005940(1+n));
    A331410(n) = if(!bitand(n,n-1),0,1+A331410(n+(n/vecmax(factor(n)[, 1]))));
    Aux336394(n) = [A278222(n), A331410(n)];
    v336394 = rgs_transform(vector(up_to, n, Aux336394(n)));
    A336394(n) = v336394[n];

A336934 Lexicographically earliest infinite sequence such that a(i) = a(j) => A007733(i) = A007733(j) and A336158(i) = A336158(j), for all i, j >= 1.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 10 2020

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A007733(n), A336158(n)].
For all i, j: A324400(i) = A324400(j) => A003602(i) = A003602(j) => a(i) = a(j).

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; };
    A007733(n) = znorder(Mod(2, n/2^valuation(n, 2))); \\ From A007733
    A000265(n) = (n>>valuation(n,2));
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A336158(n) = A046523(A000265(n));
    Aux336934(n) = [A007733(n), A336158(n)];
    v336934 = rgs_transform(vector(up_to, n, Aux336934(n)));
    A336934(n) = v336934[n];

A336936 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = [A007733(n), A329697(n), A331410(n)], for all i, j >= 1.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 11 2020

Keywords

Comments

Restricted growth sequence transform of the triplet [A007733(n), A329697(n), A331410(n)], or equally, of the ordered pair [A007733(n), A335880(n)].
For all i, j: A324400(i) = A324400(j) => A003602(i) = A003602(j) => a(i) = a(j).

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; };
    A007733(n) = znorder(Mod(2, n/2^valuation(n, 2))); \\ From A007733
    A329697(n) = if(!bitand(n,n-1),0,1+A329697(n-(n/vecmax(factor(n)[, 1]))));
    A331410(n) = if(!bitand(n,n-1),0,1+A331410(n+(n/vecmax(factor(n)[, 1]))));
    Aux336936(n) = [A007733(n), A329697(n), A331410(n)];
    v336936 = rgs_transform(vector(up_to, n, Aux336936(n)));
    A336936(n) = v336936[n];

A349448 Dirichlet convolution of A000265 (odd part of n) with A349134 (Dirichlet inverse of Kimberling's paraphrases).

Original entry on oeis.org

1, 0, 1, 0, 2, 0, 3, 0, 2, 0, 5, 0, 6, 0, 0, 0, 8, 0, 9, 0, 0, 0, 11, 0, 6, 0, 4, 0, 14, 0, 15, 0, 0, 0, 0, 0, 18, 0, 0, 0, 20, 0, 21, 0, -2, 0, 23, 0, 12, 0, 0, 0, 26, 0, 0, 0, 0, 0, 29, 0, 30, 0, -3, 0, 0, 0, 33, 0, 0, 0, 35, 0, 36, 0, -4, 0, 0, 0, 39, 0, 8, 0, 41, 0, 0, 0, 0, 0, 44, 0, 0, 0, 0, 0, 0, 0, 48, 0
Offset: 1

Views

Author

Antti Karttunen, Nov 19 2021

Keywords

Crossrefs

Cf. A000265, A003602, A349134, A349447 (Dirichlet inverse).
Cf. also A349432, A349445.

Programs

  • Mathematica
    k[n_] := (n / 2^IntegerExponent[n, 2] + 1)/2; kinv[1] = 1; kinv[n_] := kinv[n] = -DivisorSum[n, kinv[#]*k[n/#] &, # < n &]; a[n_] := DivisorSum[n, # / 2^IntegerExponent[#, 2] * kinv[n/#] &]; Array[a, 100] (* Amiram Eldar, Nov 19 2021 *)
  • PARI
    A000265(n) = (n >> valuation(n, 2));
    A003602(n) = (1+(n>>valuation(n,2)))/2;
    memoA349134 = Map();
    A349134(n) = if(1==n,1,my(v); if(mapisdefined(memoA349134,n,&v), v, v = -sumdiv(n,d,if(dA003602(n/d)*A349134(d),0)); mapput(memoA349134,n,v); (v)));
    A349448(n) = sumdiv(n,d,A000265(d)*A349134(n/d));

Formula

a(n) = Sum_{d|n} A000265(d) * A349134(n/d).
From Bernard Schott, Dec 18 2021: (Start)
If p is an odd prime, a(p) = (p-1)/2.
If n is even, a(n) = 0. (End)

A351035 Lexicographically earliest infinite sequence such that a(i) = a(j) => A347385(i) = A347385(j) and A336158(i) = A336158(j), for all i, j >= 1.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jan 30 2022

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A347385(n), A336158(n)], where A347385(n) is the Dedekind psi function applied to the odd part of n, i.e., A001615(A000265(n)), and A336158(n) is the least representative of the prime signature of the odd part of n.
For all i, j >= 1: A003602(i) = A003602(j) => a(i) = a(j).

Examples

			a(33) = a(35) as both 33 = 3*11 and 35 = 5*7 are odd nonsquare semiprimes, thus A336158 gives equal values for them, and also A347385(33) = A001615(33) = A347385(35) = A001615(35) = 48.
		

Crossrefs

Differs from A347374 for the first time at n=103, where a(103) = 48, while A347374(103) = 30.
Differs from A351036 for the first time at n=175, where a(175) = 78, while A351036(175) = 80.

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; };
    A000265(n) = (n>>valuation(n,2));
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A336158(n) = A046523(A000265(n));
    A347385(n) = if(1==n,n, my(f=factor(n>>valuation(n, 2))); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1)));
    Aux351035(n) = [A347385(n), A336158(n)];
    v351035 = rgs_transform(vector(up_to, n, Aux351035(n)));
    A351035(n) = v351035[n];

A351036 Lexicographically earliest infinite sequence such that a(i) = a(j) => A000593(i) = A000593(j) and A336158(i) = A336158(j), for all i, j >= 1.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jan 30 2022

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A000593(n), A336158(n)], where A000593(n) is the sum of odd divisors of n, and A336158(n) is the least representative of the prime signature of the odd part of n.
For all i, j:
A003602(i) = A003602(j) => A351040(i) = A351040(j) => a(i) = a(j),
a(i) = a(j) => A113415(i) = A113415(j).

Crossrefs

Cf. also A351037.
Differs from A347374 for the first time at n=103, where a(103) = 48, while A347374(103) = 30.
Differs from A351035 for the first time at n=175, where a(175) = 80, while A351035(175) = 78.
Differs from A351040 for the first time at n=637, where a(637) = 261, while A351040(637) = 272.

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; };
    A000265(n) = (n>>valuation(n,2));
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
    A336158(n) = A046523(A000265(n));
    A000593(n) = sigma(A000265(n));
    Aux351036(n) = [A000593(n), A336158(n)];
    v351036 = rgs_transform(vector(up_to, n, Aux351036(n)));
    A351036(n) = v351036[n];

A353367 Sum of A110963 and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 1, 0, 2, 0, 1, 1, 4, 0, 1, 0, 2, 4, 1, 0, 5, 0, 2, 2, 4, 0, 1, 4, 8, 5, 1, 0, -2, 0, 1, 4, 10, 4, 3, 0, 6, 8, 2, 0, 10, 0, 2, 8, 4, 0, 1, 1, 10, 10, 4, 0, 3, 8, 1, 6, 16, 0, 1, 0, 2, 15, 1, 16, 14, 0, 5, 4, 6, 0, 3, 0, 20, 6, 3, 4, -2, 0, 2, 9, 22, 0, 6, 20, 12, 16, 2, 0, 16, 8, 2, 2, 4, 12, 1, 0, 25, 24
Offset: 1

Views

Author

Antti Karttunen, Apr 18 2022

Keywords

Comments

Note the negative terms, in contrast to A349135, which apparently has none.

Crossrefs

Programs

  • PARI
    up_to = 65537;
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA003602(n) = (1+(n>>valuation(n,2)))/2;
    A110963(n) = if(n%2, A003602((1+n)/2), A110963(n/2));
    v353366 = DirInverseCorrect(vector(up_to,n,A110963(n)));
    A353366(n) = v353366[n];
    A353367(n) = (A110963(n)+A353366(n));

Formula

a(n) = A110963(n) + A353366(n).
For n > 1, a(n) = -Sum_{d|n, 1A110963(d) * A353366(n/d).
For all n >= 1, a(4*n) = A110963(n), and a(8*n-4) = A003602(n).
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