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 1-10 of 50 results. Next

A369051 Lexicographically earliest infinite sequence such that a(i) = a(j) => A003415(i) = A003415(j) and A085731(i) = A085731(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, 23, 24, 25, 26, 2, 27, 28, 29, 2, 30, 2, 31, 32, 33, 2, 34, 35, 36, 37, 38, 2, 39, 28, 40, 41, 21, 2, 40, 2, 42, 43, 44, 45, 46, 2, 47, 48, 49, 2, 50, 2, 51, 52, 53, 45, 54, 2, 55, 56, 57, 2, 58, 41, 59, 60, 61, 2, 62, 37
Offset: 1

Views

Author

Antti Karttunen, Jan 15 2024

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A003415(n), A085731(n)], or equally, of the pair [A003415(n), A083345(n)], or equally, of the pair [A083345(n), A085731(n)].
For all i, j: A369050(i) = A369050(j) => A344025(i) = A344025(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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A085731(n) = gcd(A003415(n),n);
    Aux369051(n) = [A003415(n), A085731(n)];
    v369051 = rgs_transform(vector(up_to, n, Aux369051(n)));
    A369051(n) = v369051[n];

A369008 a(n) = A085731(n) / A003557(n).

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 3, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 3, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1
Offset: 1

Views

Author

Antti Karttunen, Jan 15 2024

Keywords

Crossrefs

Cf. A342090 (positions of terms > 1).

Programs

  • Mathematica
    f[p_, e_] := If[Divisible[e, p], p, 1]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Jan 20 2024 *)
  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A003557(n) = (n/factorback(factorint(n)[, 1]));
    A369008(n) = { my(u=A003415(n)); (gcd(n,u)/A003557(n)); };
    
  • PARI
    A369008(n) = if(1==n, n, my(f=factor(n)); for(i=1, #f~, if((f[i, 2]%f[i, 1]), f[i, 1] = 1, f[i, 2] = 1)); factorback(f));

Formula

Multiplicative with a(p^e) = p if p|e, otherwise a(p^e) = 1.
For n > 1, a(n) = A342001(n) / A083345(n).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Product_{p prime} ((p^(p+1) + p^2 - 3*p +1)/(p*(p^p-1))) = 1.22775972725472961826... . - Amiram Eldar, Jan 20 2024

A373150 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(1) = 1, and for n>1, f(n) = [A003415(n), A085731(n), A373148(n)], 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, 23, 24, 25, 26, 2, 27, 28, 29, 2, 30, 2, 31, 32, 33, 2, 34, 35, 36, 37, 38, 2, 39, 28, 40, 41, 42, 2, 43, 2, 44, 45, 46, 47, 48, 2, 49, 50, 51, 2, 52, 2, 53, 54, 55, 56, 57, 2, 58, 59, 60, 2, 61, 62, 63, 64, 65, 2, 66, 67, 68, 69, 70, 71, 72, 2, 73, 74
Offset: 1

Views

Author

Antti Karttunen, May 27 2024

Keywords

Comments

Restricted growth sequence transform of the function f defined as: f(1) = 1, and for n>1, f(n) = [A003415(n), A085731(n), A373148(n)].
For all i, j >= 1:
A305800(i) = A305800(j) => a(i) = a(j),
a(i) = a(j) => A369051(i) = A369051(j),
a(i) = a(j) => A373151(i) = A373151(j) => A373143(i) = A373143(j).

Crossrefs

Differs from A369050 for the first time at n=91, where a(91)=67, while A369050(91)=37.
Differs from A300833 for the first time at n=133, where a(133)=133, while A300833(133)=50.

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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A085731(n) = gcd(A003415(n),n);
    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)); };
    A373148(n) = (A276085(n)%A003415(n));
    Aux373150(n) = if(1==n,1,[A003415(n), A085731(n), A373148(n)]);
    v373150 = rgs_transform(vector(up_to, n, Aux373150(n)));
    A373150(n) = v373150[n];

A359577 Dirichlet inverse of A085731, where A085731 is the greatest common divisor of n and the arithmetic derivative of n.

Original entry on oeis.org

1, -1, -1, -3, -1, 1, -1, 3, -2, 1, -1, 3, -1, 1, 1, -3, -1, 2, -1, 3, 1, 1, -1, -3, -4, 1, -22, 3, -1, -1, -1, 3, 1, 1, 1, 6, -1, 1, 1, -3, -1, -1, -1, 3, 2, 1, -1, 3, -6, 4, 1, 3, -1, 22, 1, -3, 1, 1, -1, -3, -1, 1, 2, -3, 1, -1, -1, 3, 1, -1, -1, -6, -1, 1, 4, 3, 1, -1, -1, 3, 28, 1, -1, -3, 1, 1, 1, -3, -1, -2, 1, 3, 1, 1, 1, -3, -1, 6, 2, 12, -1, -1, -1, -3, -1
Offset: 1

Views

Author

Antti Karttunen, Jan 06 2023

Keywords

Comments

Multiplicative because A085731 is.

Crossrefs

Cf. A003415, A085731, A038838 (positions of even terms), A122132 (of odd terms), A353627 (parity of terms).

Programs

  • Maple
    g:= proc(n) option remember;
          igcd(n, n*add(i[2]/i[1], i=ifactors(n)[2]))
        end:
    a:= proc(n) option remember; `if`(n=1, 1, -add(
          a(d)*g(n/d), d=numtheory[divisors](n) minus {n}))
        end:
    seq(a(n), n=1..120);  # Alois P. Heinz, Jan 07 2023
  • Mathematica
    d[0] = d[1] = 0; d[n_] := n * Plus @@ ((Last[#]/First[#]) & /@ FactorInteger[n]); s[n_] := GCD[n, d[n]]; a[1] = 1; a[n_] := a[n] = -DivisorSum[n, s[n/#]*a[#] &, # < n &]; Array[a, 100] (* Amiram Eldar, Jan 07 2023 *)

Formula

a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, dA085731(n/d) * a(d).

A373152 Lexicographically earliest infinite sequence such that a(i) = a(j) => A085731(i) = A085731(j) and A373145(i) = A373145(j), for all i, j >= 1.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jun 03 2024

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A085731(n), A373145(n)], i.e., the ordered pair [gcd(n, A003415(n)), gcd(A003415(n), A276085(n))].
For all i, j >= 1: A373150(i) = A373150(j) => a(i) = a(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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*prod(i=1,primepi(f[k, 1]-1),prime(i))); };
    Aux373152(n) = [gcd(n, A003415(n)), gcd(A003415(n), A276085(n))];
    v373152 = rgs_transform(vector(up_to, n, Aux373152(n)));
    A373152(n) = v373152[n];

A373379 Lexicographically earliest infinite sequence such that a(i) = a(j) => A003415(i) = A003415(j), A085731(i) = A085731(j) and A107463(i) = A107463(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, 23, 24, 25, 26, 2, 27, 28, 29, 2, 30, 2, 31, 32, 33, 2, 34, 35, 36, 37, 38, 2, 39, 28, 40, 41, 42, 2, 43, 2, 44, 45, 46, 47, 48, 2, 49, 50, 51, 2, 52, 2, 53, 54, 55, 47, 56, 2, 57, 58, 59, 2, 60, 41, 61, 62, 63, 2, 64, 37, 65, 66, 67, 68, 69, 2, 70, 71, 72
Offset: 1

Views

Author

Antti Karttunen, Jun 03 2024

Keywords

Comments

Restricted growth sequence transform of the triple [A003415(n), A085731(n), A107463(n)].
For all i, j >= 1:
A305800(i) = A305800(j) => a(i) = a(j),
a(i) = a(j) => A369051(i) = A369051(j),
a(i) = a(j) => A373363(i) = A373363(j),
a(i) = a(j) => A373364(i) = A373364(j).
Starts to differ from A300235 at n=153. - R. J. Mathar, Jun 06 2024

Crossrefs

Differs from A305895, A327931, and A353560 for the first time at n=1610, where a(1610) = 1112, while A305895(1610) = A327931(1610) = A353560(1610) = 1210.
Cf. also A373150, A373152, A373380.

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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A085731(n) = gcd(A003415(n),n);
    A001414(n) = ((n=factor(n))[, 1]~*n[, 2]);
    A107463(n) = if(n<=1,n,if(isprime(n),1,A001414(n)));
    Aux373379(n) = [A003415(n), A085731(n), A107463(n)];
    v373379 = rgs_transform(vector(up_to, n, Aux373379(n)));
    A373379(n) = v373379[n];

A268398 Partial sums of A085731.

Original entry on oeis.org

1, 2, 3, 7, 8, 9, 10, 14, 17, 18, 19, 23, 24, 25, 26, 42, 43, 46, 47, 51, 52, 53, 54, 58, 63, 64, 91, 95, 96, 97, 98, 114, 115, 116, 117, 129, 130, 131, 132, 136, 137, 138, 139, 143, 146, 147, 148, 164, 171, 176, 177, 181, 182, 209, 210, 214, 215, 216, 217
Offset: 1

Views

Author

Peter Kagey, Feb 03 2016

Keywords

Crossrefs

Programs

  • Mathematica
    Accumulate@ Table[GCD[n, If[Abs@ n < 2, 0, n Total[#2/#1 & @@@ FactorInteger@ Abs@ n]]], {n, 58}] (* Michael De Vlieger, Feb 14 2016, after Michael Somos at A003415  *)
    Accumulate@ Table[GCD[n, If[Abs@ n < 2, 0, n Total[#2/#1 & @@@ FactorInteger@ Abs@ n]]], {n, 58}] (* Michael De Vlieger, Feb 14 2016 *)
  • PARI
    a085731(n) = {my(f = factor(n)); for (i=1, #f~, if (f[i,2] % f[i,1], f[i,2]--);); factorback(f);}
    a(n) = sum(k=1, n, a085731(k)); \\ Michel Marcus, Feb 14 2016
  • Ruby
    require 'prime'
    def a003415(n)
      return 0 if n == 1
      return 1 if Prime.prime?(n)
      a = Prime.each.find { |i| n % i == 0 }
      a * a003415(n/a) + n/a * a003415(a)
    end
    def a268398(n)
      sum = 0
      (1..n).map { |n| sum += a003415(n).gcd(n) }.last
    end
    

A373268 Lexicographically earliest infinite sequence such that a(i) = a(j) => A003415(i) = A003415(j), A085731(i) = A085731(j) and A373145(i) = A373145(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, 23, 24, 25, 26, 2, 27, 28, 29, 2, 30, 2, 31, 32, 33, 2, 34, 35, 36, 37, 38, 2, 39, 28, 40, 41, 21, 2, 42, 2, 43, 44, 45, 46, 47, 2, 48, 49, 50, 2, 51, 2, 52, 53, 54, 46, 55, 2, 56, 57, 58, 2, 59, 41, 60, 61, 62, 2, 63, 64, 65, 66, 67, 68, 69, 2, 70, 71, 72, 2, 73, 2, 74, 55
Offset: 1

Views

Author

Antti Karttunen, Jun 09 2024

Keywords

Comments

Restricted growth sequence transform of the triple [A003415(n), A085731(n), A373145(n)].
For all i, j >= 1:
A373150(i) = A373150(j) => a(i) = a(j),
a(i) = a(j) => A373151(i) = A373151(j) => A373485(i) = A373485(j),
a(i) = a(j) => A373152(i) = A373152(j),
a(i) = a(j) => A373486(i) = A373486(j).

Crossrefs

Differs from A344025 and A369046 for the first time at n=91, where a(91) = 64, while A344025(91) = A369046(91) = 37.
Differs from A351236 for the first time at n=143, where a(143) = 100, while A351236(143) = 68.

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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*prod(i=1,primepi(f[k, 1]-1),prime(i))); };
    Aux373268(n) = { my(d=A003415(n)); [d, gcd(d,n), gcd(d, A276085(n))]; };
    v373268 = rgs_transform(vector(up_to, n, Aux373268(n)));
    A373268(n) = v373268[n];

A373980 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = [A003415(n), A085731(n), A181819(n), A373247(n)], for all i, j >= 1.

Original entry on oeis.org

1, 2, 3, 4, 3, 5, 3, 6, 7, 8, 3, 9, 3, 10, 11, 12, 3, 13, 3, 14, 15, 16, 3, 17, 18, 19, 20, 21, 3, 22, 3, 23, 24, 25, 26, 27, 3, 28, 29, 30, 3, 31, 3, 32, 33, 34, 3, 35, 36, 37, 38, 39, 3, 40, 29, 41, 42, 43, 3, 44, 3, 45, 46, 47, 48, 49, 3, 50, 51, 52, 3, 53, 3, 54, 55, 56, 48, 57, 3, 58, 59, 60, 3, 61, 42, 62, 63, 64, 3, 65, 38, 66, 67, 68, 69, 70, 3, 71, 72
Offset: 1

Views

Author

Antti Karttunen, Jun 24 2024

Keywords

Comments

Restricted growth sequence transform of the quadruple [A003415(n), A085731(n), A181819(n), A373247(n)].
For all i, j >= 1:
A305801(i) = A305801(j) => a(i) = a(j),
a(i) = a(j) => A300249(i) = A300249(j) => A101296(i) = A101296(j),
a(i) = a(j) => A369051(i) = A369051(j),
a(i) = a(j) => A373250(i) = A373250(j).

Crossrefs

Differs from A353520 and A361021 first at n=130, where a(130) = 82, while A353520(130) = A361021(130) = 96.

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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A181819(n) = factorback(apply(e->prime(e),(factor(n)[,2])));
    Aux373980(n) = { my(d=A003415(n), s=A181819(n)); [d, s, gcd(n,d), n%s]; };
    v373980 = rgs_transform(vector(up_to, n, Aux373980(n)));
    A373980(n) = v373980[n];

A374040 Lexicographically earliest infinite sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = [A003415(n), A085731(n), A007814(n), A007949(n)], for all i, j >= 1.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 5, 7, 8, 9, 5, 10, 5, 11, 12, 13, 5, 14, 5, 15, 16, 17, 5, 18, 19, 20, 21, 22, 5, 23, 5, 24, 25, 26, 27, 28, 5, 29, 30, 31, 5, 32, 5, 33, 34, 35, 5, 36, 37, 38, 39, 40, 5, 41, 42, 43, 44, 45, 5, 46, 5, 47, 48, 49, 50, 51, 5, 52, 53, 54, 5, 55, 5, 56, 57, 58, 50, 59, 5, 60, 61, 62, 5, 63, 64, 65, 66, 67, 5, 68, 69, 70, 71, 72, 73, 74, 5, 75
Offset: 1

Views

Author

Antti Karttunen, Jul 01 2024

Keywords

Comments

Restricted growth sequence transform of the quadruple [A003415(n), A085731(n), A007814(n), A007949(n)].
For all i, j >= 1:
A305900(i) = A305900(j) => a(i) = a(j),
a(i) = a(j) => A322026(i) = A322026(j),
a(i) = a(j) => A369051(i) = A369051(j) => A083345(i) = A083345(j),
a(i) = a(j) => b(i) = b(j), where b can be any of the sequences listed at the crossrefs-section, under "some of the other matched sequences".

Crossrefs

Some of the other matched sequences (see comments): A083345, A359430, A369001, A369004, A369643, A369658, A373143, A373474, A373483.
Cf. also A322026, A353521, A369051, A373268, A372573, A374131 for similar and related constructions.
Differs from A305900 first at n=77, where a(77) = 50, while A305900(77) = 59.

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; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    Aux374040(n) = { my(d=A003415(n)); [d, gcd(n,d), valuation(n,2), valuation(n,3)]; };
    v374040 = rgs_transform(vector(up_to, n, Aux374040(n)));
    A374040(n) = v374040[n];
Showing 1-10 of 50 results. Next