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 1-3 of 3 results.

A357325 a(n) is the unique number m such that A034460(m) = A357324(n).

Original entry on oeis.org

6, 15, 21, 35, 250, 138, 4192, 10048, 6112, 748, 20736, 5968, 802, 12256, 41728, 3592, 498, 53632, 8656, 80128, 2284, 2308, 36352, 2372, 10288, 5272, 11728, 84352, 1594, 630, 6472, 48448, 6616, 50368, 1426, 1762, 102016, 172288, 32416, 8872, 2328, 9544, 19408
Offset: 1

Views

Author

Amiram Eldar, Sep 24 2022

Keywords

Crossrefs

The unitary version of A357313.

Programs

  • Mathematica
    us[1] = 0; us[n_] := Times @@ (1 + Power @@@ FactorInteger[n]) - n; m = 1500; v = s = Table[0, {m}]; Do[u = us[k]; If[2 <= u <= m, v[[u]]++; s[[u]] = k], {k, 1, m^2}]; s[[Position[v, 1] // Flatten]]

Formula

A034460(a(n)) = A357324(n).

A361420 a(n) is the unique number m such that A126168(m) = A361419(n).

Original entry on oeis.org

1, 6, 8, 15, 21, 52, 58, 82, 106, 118, 268, 158, 356, 1264, 1296, 388, 202, 214, 226, 130, 508, 524, 1936, 160, 138, 298, 692, 2608, 358, 3088, 288, 446, 454, 466, 932, 478, 432, 348, 1792, 538, 562, 578, 586, 12032, 1268, 748, 20736, 1348, 694, 706, 26368, 544, 758
Offset: 1

Views

Author

Amiram Eldar, Mar 11 2023

Keywords

Crossrefs

Similar sequences: A357313, A357325.

Programs

  • Mathematica
    f[p_, e_] := Module[{b = IntegerDigits[e, 2]}, m = Length[b]; Product[If[b[[j]] > 0, 1 + p^(2^(m - j)), 1], {j, 1, m}]]; is[1] = 0; is[n_] := Times @@ f @@@ FactorInteger[n] - n;
    seq[max_] := Module[{v = s = Table[0, {max}], i}, Do[i = is[k] + 1; If[i <= max, v[[i]]++; s[[i]] = k], {k, 1, max^2}]; s[[Position[v, 1] // Flatten]]];
    seq[500]
  • PARI
    s(n) = {my(f = factor(n), b); prod(i=1, #f~, b = binary(f[i, 2]); prod(k=1, #b, if(b[k], f[i, 1]^(2^(#b-k)) + 1, 1))) - n; }
    lista(nmax) = {my(v = w = vector(nmax+1)); for(k=1, nmax^2, i = s(k) + 1; if(i <= nmax+1, v[i] += 1; w[i] = k)); for(i = 1, nmax+1, if(v[i] == 1, print1(w[i], ", "))); }

Formula

A126168(a(n)) = A361419(n).

A372743 a(n) is the unique number m such that A336563(m) = A372742(n).

Original entry on oeis.org

4, 9, 25, 49, 121, 27, 169, 289, 24, 361, 529, 54, 841, 961, 36, 1369, 1681, 1849, 2209, 2809, 343, 3481, 3721, 4489, 5041, 5329, 6241, 100, 6889, 189, 7921, 72, 9409, 112, 10201, 10609, 11449, 11881, 686, 12769, 16129, 17161, 225, 18769, 19321, 196, 22201, 160
Offset: 1

Views

Author

Amiram Eldar, May 12 2024

Keywords

Comments

Includes all the squares of primes (A001248).

Crossrefs

A001248 is a subsequence.
Similar sequences: A357313, A357325, A361420.

Programs

  • Mathematica
    f[p_, e_] := (p^(e + 1) - 1)/(p - 1) - 1; s[1] = 0; s[n_] := Times @@ f @@@ FactorInteger[n] - n; seq[max_] := Module[{v = w = Table[0, {max}], i}, Do[i = s[k]; If[1 <= i <= max, v[[i]]++; w[[i]] = k], {k, 1, max^2}]; w[[Position[v, 1] // Flatten]]]; seq[200]
  • PARI
    s(n) = {my(f = factor(n)); prod(i = 1, #f~, (f[i, 1]^(f[i, 2] + 1) - 1)/(f[i, 1] -1) - 1) - n;}
    lista(nmax) = {my(v = w = vector(nmax), i); for(k = 1, nmax^2, i = s(k); if(i > 0 && i <= nmax, v[i]++; w[i] = k)); for(k = 1, nmax, if(v[k] == 1, print1(w[k], ", ")));}

Formula

A336563(a(n)) = A372742(n).
Showing 1-3 of 3 results.