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.

Previous Showing 51-56 of 56 results.

A249810 a(1) = 0, a(n) = A078898(A003961(n)).

Original entry on oeis.org

0, 1, 1, 2, 1, 3, 1, 5, 2, 4, 1, 8, 1, 6, 3, 14, 1, 13, 1, 11, 4, 7, 1, 23, 2, 9, 9, 17, 1, 18, 1, 41, 5, 10, 3, 38, 1, 12, 6, 32, 1, 28, 1, 20, 12, 15, 1, 68, 2, 25, 7, 26, 1, 63, 4, 50, 8, 16, 1, 53, 1, 19, 19, 122, 5, 33, 1, 29, 10, 39, 1, 113, 1, 21, 17, 35, 3, 43, 1, 95, 42, 22, 1, 83, 6, 24, 11, 59, 1, 88, 4, 44, 13, 27, 7, 203
Offset: 1

Views

Author

Antti Karttunen, Dec 08 2014

Keywords

Crossrefs

Programs

Formula

a(1) = 0, a(n) = A078898(A003961(n)).
a(1) = 0, a(n) = A078898(n) + A249820(n).

A346477 Dirichlet inverse of A346476.

Original entry on oeis.org

1, -1, -1, 2, -3, 5, -3, 2, 8, 13, -9, -2, -9, 17, 11, 8, -15, -8, -15, -12, 19, 37, -17, 18, 8, 41, -4, -12, -27, -33, -25, 20, 37, 61, 25, 56, -33, 65, 35, 38, -39, -45, -39, -42, -36, 77, -41, 32, 32, -20, 53, -42, -47, 96, 35, 58, 61, 109, -57, 132, -55, 109, -48, 56, 43, -121, -63, -72, 71, -109, -69, 56
Offset: 1

Views

Author

Antti Karttunen, Jul 29 2021

Keywords

Crossrefs

Programs

  • PARI
    up_to = 16384;
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA346476(n) = (n+n-A250469(n));
    v346477 = DirInverseCorrect(vector(up_to,n,A346476(n)));
    A346477(n) = v346477[n];

Formula

a(1) = 1; and for n > 2, a(n) = -Sum_{d|n, dA346476(n/d).
a(n) = A346478(n) - A346476(n).
a(p) = A252748(p) = A346248(p) = -A346476(p) = -A062234(A000720(p)), for any prime p.

A346478 Sum of A346476 and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 1, 0, 2, 0, -3, 1, 6, 0, -11, 0, 6, 6, -5, 0, -23, 0, -29, 6, 18, 0, -3, 9, 18, -15, -37, 0, -60, 0, -9, 18, 30, 18, 23, 0, 30, 18, 1, 0, -84, 0, -83, -61, 34, 0, -13, 9, -67, 30, -91, 0, 45, 54, 5, 30, 54, 0, 75, 0, 50, -77, -5, 54, -184, 0, -137, 34, -176, 0, -13, 0, 66, -55, -145, 54, -188, 0, -37, 49
Offset: 1

Views

Author

Antti Karttunen, Jul 30 2021

Keywords

Crossrefs

Programs

  • PARI
    up_to = 16384;
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA346476(n) = (n+n-A250469(n));
    v346477 = DirInverseCorrect(vector(up_to,n,A346476(n)));
    A346477(n) = v346477[n];
    A346478(n) = (A346476(n)+A346477(n));

Formula

a(n) = A346476(n) + A346477(n).
a(1) = 2; and for n > 2, a(n) = -Sum_{d|n, 1A346476(n/d) * A346477(d).

A302043 a(n) = n - A302042(n); an analog of A060681 based on the sieve of Eratosthenes (A083221).

Original entry on oeis.org

0, 1, 2, 2, 4, 3, 6, 4, 6, 5, 10, 6, 12, 7, 10, 8, 16, 9, 18, 10, 12, 11, 22, 12, 20, 13, 20, 14, 28, 15, 30, 16, 18, 17, 28, 18, 36, 19, 28, 20, 40, 21, 42, 22, 24, 23, 46, 24, 42, 25, 26, 26, 52, 27, 30, 28, 30, 29, 58, 30, 60, 31, 50, 32, 54, 33, 66, 34, 36, 35, 70, 36, 72, 37, 58, 38, 66, 39, 78, 40, 42, 41, 82, 42, 50, 43, 52, 44, 88, 45, 42
Offset: 1

Views

Author

Antti Karttunen, Mar 31 2018

Keywords

Comments

An analog of A060681 based on the sieve of Eratosthenes (A083221).

Crossrefs

Programs

Formula

a(n) = n - A302042(n).

A302046 A filter sequence analogous to A101296 for nonstandard factorization based on the sieve of Eratosthenes (A083221).

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 5, 3, 4, 2, 6, 2, 4, 4, 7, 2, 6, 2, 6, 5, 4, 2, 8, 3, 4, 4, 6, 2, 9, 2, 10, 6, 4, 4, 11, 2, 4, 4, 8, 2, 8, 2, 6, 7, 4, 2, 12, 3, 6, 6, 6, 2, 9, 5, 8, 6, 4, 2, 13, 2, 4, 4, 14, 4, 13, 2, 6, 8, 9, 2, 15, 2, 4, 4, 6, 4, 9, 2, 12, 6, 4, 2, 15, 6, 4, 9, 8, 2, 12, 5, 6, 10, 4, 4, 16, 2, 6, 4, 11, 2, 13, 2, 8, 11
Offset: 1

Views

Author

Antti Karttunen, Mar 31 2018

Keywords

Comments

Restricted growth sequence transform of A278524.
See A302042 for the description of the nonstandard factorization employed here.
For all i, j:
a(i) = a(j) => A253557(i) = A253557(j).
a(i) = a(j) => A302041(i) = A302041(j).
a(i) = a(j) => A302050(i) = A302050(j).
a(i) = a(j) => A302051(i) = A302051(j) => A302052(i) = A302052(j).

Crossrefs

Programs

  • PARI
    up_to = 32769;
    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; };
    write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
    A020639(n) = { if(1==n,n,vecmin(factor(n)[, 1])); };
    A078898(n) = { if(n<=1,n, my(spf=A020639(n),k=1,m=n/spf); while(m>1,if(A020639(m)>=spf,k++); m--); (k)); };
    A001511(n) = 1+valuation(n,2);
    A302045(n) = A001511(A078898(n));
    A302044(n) = if(1==n,n,my(k=0); while((n%2), n = A268674(n); k++); n = (n/2^valuation(n, 2)); while(k>0, n = A250469(n); k--); (n));
    A302041(n) = if(1==n, 0,1+A302041(A302044(n)));
    Aux302046(n) = if(1==n,n, my(k=A302041(n), v = vector(k),i=1); while(n>1,v[i] = A302045(n); n = A302044(n); i++); vecsort(v));
    write_to_bfile(1,rgs_transform(vector(up_to,n,Aux302046(n))),"b302046.txt");

A280701 a(n) = n - A280704(n).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 1, 8, 1, 10, 1, 12, 1, 14, 11, 16, 1, 18, 1, 20, 1, 22, 1, 24, 1, 14, 19, 28, 1, 30, 1, 16, 1, 34, 29, 36, 1, 20, 27, 40, 1, 42, 1, 22, 1, 46, 1, 48, 49, 26, 51, 52, 1, 54, 51, 28, 1, 58, 1, 60, 1, 32, 57, 64, 65, 66, 1, 34, 1, 70, 1, 72, 1, 38, 51, 76, 1, 78, 1, 40, 1, 82, 1, 84, 1, 44, 59, 88, 1, 90, 1, 46
Offset: 1

Views

Author

Antti Karttunen, Mar 08 2017

Keywords

Comments

Questions: Are all terms nonnegative? Where do ones occur?

Crossrefs

Programs

  • Mathematica
    f[n_] := f[n] = Which[n == 1, 1, PrimeQ@ n, NextPrime@ n, True, Times @@ Replace[FactorInteger[n], {p_, e_} :> f[p]^e, 1]]; g[n_] := If[n == 1, 0, PrimePi@ FactorInteger[n][[1, 1]]]; Function[s, MapIndexed[ Function[t, First@ #2 - t/GCD[t, f@ First@ #2]][Lookup[s, g[First@ #2] + 1][[#1]] - Boole[First@ #2 == 1]] &, #] &@ Map[Position[Lookup[s, g@ #], #][[1, 1]] &, Range@ 120]]@ PositionIndex@ Array[g, 10^4] (* Michael De Vlieger, Mar 08 2017, Version 10 *)
  • Scheme
    (define (A280701 n) (- n (A280704 n)))

Formula

a(n) = n - A280704(n) = n - (A250469(n)/gcd(A003961(n),A250469(n))).
Previous Showing 51-56 of 56 results.