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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A323173 Sum of divisors computed for conjugated prime factorization: a(n) = A000203(A122111(n)).

Original entry on oeis.org

1, 3, 7, 4, 15, 12, 31, 6, 13, 28, 63, 18, 127, 60, 39, 8, 255, 24, 511, 42, 91, 124, 1023, 24, 40, 252, 31, 90, 2047, 72, 4095, 12, 195, 508, 120, 32, 8191, 1020, 403, 56, 16383, 168, 32767, 186, 93, 2044, 65535, 36, 121, 78, 819, 378, 131071, 48, 280, 120, 1651, 4092, 262143, 96, 524287, 8188, 217, 14, 600, 360, 1048575, 762, 3315, 234
Offset: 1

Views

Author

Antti Karttunen, Jan 10 2019

Keywords

Crossrefs

Programs

  • Mathematica
    A122111[n_] := Product[Prime[Sum[If[j < i, 0, 1], {j, #}]], {i, Max[#]}]&[ Flatten[Table[Table[PrimePi[f[[1]]], {f[[2]]}], {f, FactorInteger[n]}]]];
    a[n_] := With[{k = A122111[n]}, DivisorSigma[1, k]];
    Array[a, 70] (* Jean-François Alcover, Sep 23 2020 *)
  • PARI
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
    A323173(n) = sigma(A122111(n));

Formula

a(n) = A000203(A122111(n)).
a(n) = 2*A122111(n) - A323174(n).
a(n) = A322819(n) * A038712(A122111(n)).

A336124 a(n) = A122111(n) mod 4.

Original entry on oeis.org

1, 2, 0, 3, 0, 2, 0, 1, 1, 0, 0, 2, 0, 0, 2, 3, 0, 3, 0, 0, 0, 0, 0, 2, 3, 0, 1, 0, 0, 2, 0, 3, 0, 0, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 1, 1, 0, 0, 0, 3, 0, 0, 0, 0, 0, 2, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 3, 0, 2, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 3, 0, 3, 0, 0, 0, 0, 2
Offset: 1

Views

Author

Antti Karttunen, Jul 15 2020

Keywords

Crossrefs

Programs

  • PARI
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
    A336124(n) = (A122111(n)%4);

Formula

a(n) = A010873(A122111(n)).

A322819 a(n) = A000593(A122111(n)).

Original entry on oeis.org

1, 1, 1, 4, 1, 4, 1, 6, 13, 4, 1, 6, 1, 4, 13, 8, 1, 24, 1, 6, 13, 4, 1, 8, 40, 4, 31, 6, 1, 24, 1, 12, 13, 4, 40, 32, 1, 4, 13, 8, 1, 24, 1, 6, 31, 4, 1, 12, 121, 78, 13, 6, 1, 48, 40, 8, 13, 4, 1, 32, 1, 4, 31, 14, 40, 24, 1, 6, 13, 78, 1, 48, 1, 4, 124, 6, 121, 24, 1, 12, 57, 4, 1, 32, 40, 4, 13, 8, 1, 48, 121, 6, 13, 4, 40, 14, 1, 240
Offset: 1

Views

Author

Antti Karttunen, Dec 27 2018

Keywords

Crossrefs

Programs

Formula

a(n) = A000593(A122111(n)).

A322865 a(n) = A000265(A122111(n)).

Original entry on oeis.org

1, 1, 1, 3, 1, 3, 1, 5, 9, 3, 1, 5, 1, 3, 9, 7, 1, 15, 1, 5, 9, 3, 1, 7, 27, 3, 25, 5, 1, 15, 1, 11, 9, 3, 27, 21, 1, 3, 9, 7, 1, 15, 1, 5, 25, 3, 1, 11, 81, 45, 9, 5, 1, 35, 27, 7, 9, 3, 1, 21, 1, 3, 25, 13, 27, 15, 1, 5, 9, 45, 1, 33, 1, 3, 75, 5, 81, 15, 1, 11, 49, 3, 1, 21, 27, 3, 9, 7, 1, 35, 81, 5, 9, 3, 27, 13, 1, 135, 25, 63, 1, 15, 1, 7, 75
Offset: 1

Views

Author

Antti Karttunen, Dec 30 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Array[#/2^IntegerExponent[#, 2] &@ If[# < 3, 1, Block[{k = #, m = 0}, Times @@ Power @@@ Table[k -= m; k = DeleteCases[k, 0]; {Prime@ Length@ k, m = Min@ k}, Length@ Union@ k]] &@ Catenate[ConstantArray[PrimePi[#1], #2] & @@@ FactorInteger@ #]] &, 105] (* Michael De Vlieger, Dec 31 2018, after JungHwan Min at A122111 *)
  • PARI
    A000265(n) = (n>>valuation(n, 2));
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
    A322865(n) = A000265(A122111(n));

Formula

a(n) = A000265(A122111(n)).
a(n) = A122111(A322820(n)).
A000005(a(n)) = A322813(n).
A000203(a(n)) = A322819(n).
A122111(a(n)) = A322820(n).
A000120(a(n)) = A322867(n).

A336120 a(n) = A292383(A122111(n)).

Original entry on oeis.org

0, 0, 0, 1, 0, 2, 0, 2, 0, 4, 0, 4, 0, 8, 0, 5, 0, 5, 0, 8, 0, 16, 0, 10, 1, 32, 0, 16, 0, 10, 0, 11, 0, 64, 2, 8, 0, 128, 0, 20, 0, 20, 0, 32, 0, 256, 0, 22, 0, 8, 0, 64, 0, 11, 4, 40, 0, 512, 0, 16, 0, 1024, 0, 22, 8, 40, 0, 128, 0, 16, 0, 20, 0, 2048, 1, 256, 0, 80, 0, 44, 0, 4096, 0, 32, 16, 8192, 0, 80, 0, 22, 0, 512, 0, 16384, 32, 44, 0, 17, 0, 17, 0
Offset: 1

Views

Author

Antti Karttunen, Jul 14 2020

Keywords

Crossrefs

Programs

  • PARI
    \\ Uses also code given in A336124:
    A253553(n) = if(n<=2,1,my(f=factor(n), k=#f~); if(f[k,2]>1,f[k,2]--,f[k,1] = precprime(f[k,1]-1)); factorback(f));
    A336120(n) = if(1==n,0,(3==A336124(n))+(2*A336120(A253553(n))));

Formula

a(1) = 0, and for n > 1, a(n) = [A122111(n) == 3 (mod 4)] + 2*a(A253553(n)).
a(n) = A292383(A122111(n)).
a(n) = A253566(n) - A336125(n).
A000120(a(n)) = A336121(n).

A244982 Permutation of natural numbers: a(n) = A243285(A122111(2*n)).

Original entry on oeis.org

1, 2, 4, 3, 8, 6, 18, 5, 11, 14, 38, 10, 79, 30, 22, 7, 164, 15, 337, 20, 47, 64, 694, 16, 35, 134, 26, 43, 1419, 32, 2888, 9, 100, 279, 73, 24, 5850, 575, 208, 34, 11822, 67, 23836, 92, 56, 1177, 47975, 19, 112, 50, 428, 193, 96431, 42, 152, 71, 877, 2395, 193614, 52
Offset: 1

Views

Author

Antti Karttunen, Jul 20 2014

Keywords

Crossrefs

Programs

Formula

a(n) = A243285(A122111(2*n)).

A244984 Permutation of natural numbers: a(n) = A243283(A122111((2*n)-1)).

Original entry on oeis.org

1, 2, 3, 5, 4, 9, 14, 6, 23, 37, 10, 58, 8, 7, 90, 143, 15, 13, 225, 24, 355, 563, 12, 894, 17, 38, 1426, 20, 60, 2277, 3643, 19, 31, 5839, 96, 9398, 15155, 16, 27, 24518, 11, 39758, 50, 153, 64607, 42, 242, 80, 105250, 30, 171874, 281237, 26
Offset: 1

Views

Author

Antti Karttunen, Jul 21 2014

Keywords

Crossrefs

Programs

Formula

a(n) = A243283(A122111((2*n)-1)).
a(n) = A243283(A105560((2*n)-1) * A243505(n)).
For all n >= 1, a(A006254(n)) = A244986(n+1).

A334107 a(n) = A329697(A122111(n)).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Apr 29 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Map[Length@ NestWhileList[# - #/FactorInteger[#][[-1, 1]] &, #, # != 2^IntegerExponent[#, 2] &] - 1 &, Array[Times @@ Table[Prime[LengthWhile[#1, # >= j &] /. 0 -> 1], {j, #2}] & @@ {#, Max[#]} &@ PrimePi@ Flatten[ConstantArray[#1, {#2}] & @@@ FactorInteger@ #] &, 105] ] (* Michael De Vlieger, May 14 2020, after Robert G. Wilson v at A329697 *)
  • PARI
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A122111(n) = if(1==n,n,prime(bigomega(n))*A122111(A064989(n)));
    A329697(n) = if(!bitand(n,n-1),0,1+A329697(n-(n/vecmax(factor(n)[, 1]))));
    A334107(n) = A329697(A122111(n));

Formula

a(n) = A329697(A122111(n)) = A329697(A322865(n)).
a(n) = A329697(A105560(n)) + a(A064989(n)).
For n >= 1, a(A001248(n)) = n, and these seem to be also the first occurrences of each n.

A244981 Permutation of natural numbers: a(n) = A122111(A102750(n)) / 2.

Original entry on oeis.org

1, 2, 4, 3, 8, 6, 16, 5, 32, 12, 9, 64, 128, 10, 18, 24, 256, 7, 48, 20, 512, 15, 1024, 36, 96, 27, 2048, 192, 72, 14, 4096, 30, 8192, 40, 25, 384, 16384, 11, 144, 80, 32768, 54, 28, 288, 768, 65536, 21, 131072, 1536, 50, 108, 60, 262144, 160, 576, 45, 524288, 1048576, 3072, 320, 81, 120, 2097152, 22, 6144, 4194304, 42
Offset: 1

Views

Author

Antti Karttunen, Jul 20 2014

Keywords

Crossrefs

Programs

Formula

a(n) = A122111(A102750(n)) / 2.

A244983 Permutation of natural numbers: a(1) = 1, a(n) = (1 + A122111(A070003(n-1))) / 2.

Original entry on oeis.org

1, 2, 3, 5, 4, 8, 14, 13, 6, 11, 41, 23, 18, 7, 17, 38, 25, 68, 32, 28, 122, 63, 9, 20, 113, 53, 39, 365, 95, 50, 33, 74, 203, 61, 188, 88, 10, 26, 1094, 158, 83, 46, 608, 313, 3281, 338, 123, 149, 59, 43, 221, 116, 284, 72, 263, 138, 1013, 12, 9842, 29, 1823, 248, 98, 563, 172, 60
Offset: 1

Views

Author

Antti Karttunen, Jul 21 2014

Keywords

Crossrefs

Inverse: A244984.
Related or similar permutations: A122111, A244981-A244982, A243505-A243506, A243065-A243066.

Programs

Formula

a(1) = 1, a(n) = (1 + A122111(A070003(n-1))) / 2.
For all n >= 1, a(A244986(n+1)) = A006254(n).
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