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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A331734 a(n) = A033879(A225546(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 1, 0, 5, 1, 1, -4, 1, 1, 1, 4, 1, -3, 1, -28, 1, 1, 1, -12, 41, 1, -19, -508, 1, 1, 1, 2, 1, 1, 1, 14, 1, 1, 1, -60, 1, 1, 1, -131068, -115, 1, 1, -2, 3281, -39, 1, -8589934588, 1, -51, 1, -1020, 1, 1, 1, -124, 1, 1, -2035, 6, 1, 1, 1, -36893488147419103228, 1, 1, 1, -12, 1, 1, -199, -680564733841876926926749214863536422908
Offset: 1

Views

Author

Antti Karttunen, Feb 02 2020

Keywords

Crossrefs

Cf. A323244, A323174, A324055, A324185, A324546 for other permutations of the deficiency, and also A324574, A324654.

Programs

  • PARI
    A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; };
    A331734(n) = if(issquarefree(n),1,my(f=factor(n),u=#binary(vecmax(f[, 2])),prods=vector(u,x,1),m=1,e); for(i=1,u,for(k=1,#f~, if(bitand(f[k,2],m),prods[i] *= f[k,1])); m<<=1); (2*prod(i=1,u,prime(i)^A048675(prods[i]))) - prod(i=1,u,(prime(i)^(1+A048675(prods[i]))-1)/(prime(i)-1)));

Formula

a(n) = A033879(A225546(n)) = 2*A225546(n) - A331733(n).
For all n, a(A005117(n)) = 1. [It is not known if there are 1's in any other positions. See Jianing Song's Oct 13 2019 comment in A033879.]
For a necessary condition that a(s) would be zero for any square, see A331741.

A323167 a(n) = A294898(A122111(n)).

Original entry on oeis.org

0, 0, 0, 0, 0, -2, 0, 2, 3, -6, 0, 0, 0, -14, -5, 3, 0, 2, 0, -4, -21, -30, 0, 1, 10, -62, 16, -12, 0, -16, 0, 7, -53, -126, -16, 7, 0, -254, -117, -3, 0, -52, 0, -28, 4, -510, 0, 5, 38, 8, -245, -60, 0, 19, -68, -11, -501, -1022, 0, -15, 0, -2046, -20, 9, -172, -124, 0, -124, -1013, -58, 0, 16, 0, -4094, 22, -252, -42, -268, 0, 1, 38
Offset: 1

Views

Author

Antti Karttunen, Jan 10 2019

Keywords

Crossrefs

Programs

Formula

a(n) = A294898(A122111(n)).
a(n) = A323174(n) - A322867(n).

A336317 Numbers k such that A122111(k) [conjugated prime factorization of k] is one of Ore's Harmonic numbers (in A001599).

Original entry on oeis.org

1, 6, 40, 126, 154, 204, 1716, 1914, 2772, 8580, 11264, 12090, 12540, 50960, 62790, 64350, 77748, 83200, 104720, 152320, 186116, 193440, 331890, 382720, 432768, 518364, 648788, 684684, 753480, 817344, 895356, 1083852, 1113840, 1619352, 1675044, 1743588, 1759680, 1991340, 2060322, 2360484, 2492028, 2621080, 2932800
Offset: 1

Views

Author

Antti Karttunen, Jul 19 2020

Keywords

Comments

Numbers k for which A336314(k) = A323173(k).
Sequence A122111(A001599(n)), n >= 1, sorted into ascending order. Positions of zeros in A323174 (corresponding to perfect numbers similarly mapped) is a subsequence.
Note that all terms after 1 seem to be present in A102750. This observation is equal to Ore's conjecture that there are no odd Harmonic numbers larger than one.
Also, all terms after 1 seem to be even, which would imply that apart from its initial 1, A001599 were a subsequence of A102750. However, this is false, as there are terms of A001599 not in A102750, for example 8011798098793361832960 found by David A. Corneth. Note that A122111(8011798098793361832960) = 96922193555635754403846044921625, which is thus an odd term of this sequence.

Crossrefs

Programs

  • PARI
    isA001599(n) = !((sigma(n,0)*n)%sigma(n,1));
    isA336317(n) = isA001599(A122111(n)); \\ Program for A122111 given under that entry.
    
  • PARI
    \\ Standalone program:
    isA336317(n) = if(1==n,1,my(f=factor(n),es=Vecrev(f[,2]),is=concat(apply(primepi,Vecrev(f[,1])),[0]),pri=0,d=1,s=1,x=1,p,e); for(i=1, #es, pri += es[i]; p = prime(pri); e = 1+is[i]-is[1+i]; d *= e; s *= ((p^e)-1)/(p-1); x *= (p^(e-1))); !((x*d)%s));
Previous Showing 11-13 of 13 results.