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.

A322869 a(n) = A000120(A048675(n)).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Dec 31 2018

Keywords

Crossrefs

Cf. A002110 (position of the first occurrence of n).

Programs

  • Mathematica
    Array[If[# == 1, 0, DigitCount[Total@ Map[#2*2^(PrimePi@ #1 - 1) & @@ # &, FactorInteger[#]], 2, 1]] &, 105]  (* Michael De Vlieger, Dec 31 2018 *)
  • PARI
    A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; }; \\ From A048675
    A322869(n) = hammingweight(A048675(n));

Formula

a(n) = A000120(A048675(n)) = A000120(A322821(n)).
a(n) = A001221(A097248(n)) = A001222(A097248(n)).
If n is squarefree, then a(n) = A001221(n) = A322862(n).
a(A002110(n)) = n.

A324377 a(0) = 0; for n > 0, a(n) = A000265(A005187(n)).

Original entry on oeis.org

0, 1, 3, 1, 7, 1, 5, 11, 15, 1, 9, 19, 11, 23, 25, 13, 31, 1, 17, 35, 19, 39, 41, 21, 23, 47, 49, 25, 53, 27, 7, 57, 63, 1, 33, 67, 35, 71, 73, 37, 39, 79, 81, 41, 85, 43, 11, 89, 47, 95, 97, 49, 101, 51, 13, 105, 109, 55, 7, 113, 29, 117, 119, 15, 127, 1, 65, 131, 67, 135, 137, 69, 71, 143, 145, 73, 149, 75, 19
Offset: 0

Views

Author

Antti Karttunen, Feb 28 2019

Keywords

Crossrefs

Programs

Formula

a(0) = 0; for n > 0, a(n) = A000265(A005187(n)) = A005187(n) / 2^A324379(n).
a(n) = A322821(A283477(n)).

A322868 Lexicographically earliest such sequence a that a(i) = a(j) => A278222(A048675(i)) = A278222(A048675(j)) for all i, j.

Original entry on oeis.org

1, 2, 2, 2, 2, 3, 2, 3, 2, 4, 2, 2, 2, 4, 3, 2, 2, 4, 2, 3, 4, 4, 2, 4, 2, 4, 3, 4, 2, 5, 2, 4, 4, 4, 3, 3, 2, 4, 4, 5, 2, 6, 2, 4, 2, 4, 2, 3, 2, 4, 4, 4, 2, 5, 4, 6, 4, 4, 2, 2, 2, 4, 3, 3, 4, 6, 2, 4, 4, 6, 2, 5, 2, 4, 4, 4, 3, 6, 2, 2, 2, 4, 2, 3, 4, 4, 4, 6, 2, 4, 4, 4, 4, 4, 4, 5, 2, 4, 4, 4, 2, 6, 2, 6, 5
Offset: 1

Views

Author

Antti Karttunen, Dec 31 2018

Keywords

Comments

Restricted growth sequence transform of A278222(A048675(n)), or equivalently, of A278222(A322821(n)).
For all i, j: a(i) = a(j) => A322869(i) = A322869(j).

Crossrefs

Programs

  • PARI
    up_to = 8192;
    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; };
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t };
    A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
    A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; }; \\ From A048675
    A278222(n) = A046523(A005940(1+n));
    v322868 = rgs_transform(vector(up_to,n,A278222(A048675(n))));
    A322868(n) = v322868[n];

A324286 a(n) = A002487(A048675(n)).

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 1, 2, 1, 3, 1, 1, 1, 4, 2, 1, 1, 3, 1, 2, 3, 5, 1, 3, 1, 6, 2, 3, 1, 3, 1, 3, 4, 7, 2, 2, 1, 8, 5, 3, 1, 5, 1, 4, 1, 9, 1, 2, 1, 4, 6, 5, 1, 3, 3, 5, 7, 10, 1, 1, 1, 11, 2, 2, 4, 7, 1, 6, 8, 5, 1, 3, 1, 12, 3, 7, 2, 9, 1, 1, 1, 13, 1, 2, 5, 14, 9, 7, 1, 4, 3, 8, 10, 15, 6, 3, 1, 5, 3, 3, 1, 11, 1, 9, 3
Offset: 1

Views

Author

Antti Karttunen, Feb 22 2019

Keywords

Comments

Like A323902 and A323903, this also has quite a moderate growth rate, even though some terms of A048675 soon grow quite big.

Crossrefs

Programs

  • PARI
    A002487(n) = { my(s=sign(n), a=1, b=0); n = abs(n); while(n>0, if(bitand(n, 1), b+=a, a+=b); n>>=1); (s*b); };
    A048675(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2; }; \\ From A048675
    A324286(n) = A002487(A048675(n));

Formula

a(n) = A002487(A048675(n)) = A002487(A322821(n)).
a(A283477(n)) = A324287(n).
Showing 1-4 of 4 results.