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 1-4 of 4 results.

A366804 Lexicographically earliest infinite sequence such that a(i) = a(j) => A324182(i) = A324182(j) for all i, j >= 0.

Original entry on oeis.org

1, 2, 2, 1, 2, 3, 4, 3, 2, 5, 6, 7, 8, 1, 4, 9, 2, 10, 11, 12, 13, 9, 14, 15, 16, 3, 17, 18, 8, 3, 4, 5, 2, 19, 20, 21, 22, 23, 24, 25, 26, 7, 27, 28, 29, 30, 17, 31, 32, 5, 33, 34, 35, 36, 37, 38, 16, 5, 11, 23, 8, 39, 4, 40, 2, 41, 42, 43, 44, 45, 46, 47, 48, 12, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61
Offset: 0

Views

Author

Antti Karttunen, Oct 24 2023

Keywords

Comments

Restricted growth sequence transform of A324182.

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; };
    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));
    A083254(n) = (2*eulerphi(n)-n);
    A324182(n) = A083254(A163511(n));
    v366804 = rgs_transform(vector(1+up_to,n,A324182(n-1)));
    A366804(n) = v366804[1+n];

A324185 Deficiency of n permuted by A163511: a(n) = A033879(A163511(n)) = 2*A163511(n) - sigma(A163511(n)).

Original entry on oeis.org

1, 1, 1, 2, 1, 5, 0, 4, 1, 14, -3, 19, -4, 6, 2, 6, 1, 41, -12, 94, -19, 26, 7, 41, -12, 12, -12, 22, -2, 10, 4, 10, 1, 122, -39, 469, -64, 126, 32, 286, -51, 47, -72, 148, -17, 66, 25, 109, -28, 30, -54, 102, -48, 18, -4, 58, -10, 22, -12, 38, 0, 18, 8, 12, 1, 365, -120, 2344, -199, 626, 157, 2001, -168, 222, -372, 1030, -92, 458, 172, 1198
Offset: 0

Views

Author

Antti Karttunen, Feb 17 2019

Keywords

Comments

If there are no odd perfect numbers, then all n for which a(n) is 0 are given by sequence A324200.

Crossrefs

Programs

  • PARI
    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));
    A033879(n) = (2*n-sigma(n));
    A324185(n) = A033879(A163511(n));
    
  • PARI
    A324184(n) = if(!n,1,my(p=2,mp=p*p,m=1); while(n>1, if(n%2, p=nextprime(1+p); mp = p*p, if((2==n)||!(n%4),mp *= p,m *= (mp-1)/(p-1))); n >>= 1); (m*(mp-1)/(p-1)));
    A324185(n) = (2*A163511(n)) - A324184(n);

Formula

a(n) = A033879(A163511(n)) = 2*A163511(n) - A324184(n) = 2*A163511(n) - A000203(A163511(n)).
For n > 0, a(n) = A324055(A054429(n)).

A324052 a(n) = A083254(A005940(1+n)).

Original entry on oeis.org

1, 0, 1, 0, 3, -2, 3, 0, 5, -2, 1, -4, 15, -6, 9, 0, 9, -2, 3, -4, 13, -14, 3, -8, 35, -10, 5, -12, 75, -18, 27, 0, 11, -2, 7, -4, 25, -18, 9, -8, 43, -22, -9, -28, 65, -42, 9, -16, 99, -14, 21, -20, 91, -70, 15, -24, 245, -50, 25, -36, 375, -54, 81, 0, 15, -2, 9, -4, 31, -26, 21, -8, 53, -30, -5, -36, 125, -54, 27, -16, 97, -34, 9
Offset: 0

Views

Author

Antti Karttunen, Feb 18 2019

Keywords

Crossrefs

Programs

  • PARI
    A324052(n) = { my(m1=1,m2=2,p=2); while(n, if(!(n%2), p=nextprime(1+p), m1 *= p; m2 *= (p-(1==(n%4)))); n>>=1); (m2-m1); };
    
  • PARI
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940
    A083254(n) = (2*eulerphi(n)-n);
    A324052(n) = A083254(A005940(1+n));

Formula

a(n) = A083254(A005940(1+n)).
a(n) = 2*A290077(n) - A005940(1+n).
For n >= 1, a(n) = A324182(A054429(n)).
For n >= 1, a((2^n)-1) = 0.

A324103 a(1) = 0; for n > 1, a(n) = A083254(A156552(n)).

Original entry on oeis.org

0, 1, 0, 1, 0, 3, 0, 5, -2, 3, 0, 9, 0, 15, -2, 1, 0, 11, 0, 17, -6, 7, 0, 21, -4, 31, -2, 13, 0, 3, 0, 29, -2, 39, -4, 9, 0, 255, -26, 9, 0, 35, 0, 65, -2, 135, 0, 45, -8, 15, -34, 129, 0, 27, -12, 69, -90, 575, 0, 41, 0, 679, -2, 9, -4, 19, 0, 173, -2, 39, 0, 25, 0, 3583, -2, 301, -8, 83, 0, 77, -14, 2727, 0, 5, -52, 8703, -378, 9, 0, 3
Offset: 1

Views

Author

Antti Karttunen, Feb 18 2019

Keywords

Crossrefs

Programs

Formula

a(1) = 0; for n > 1, a(n) = A083254(A156552(n)).
a(n) = 2*A324104(n) - A156552(n).
Showing 1-4 of 4 results.