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 21-22 of 22 results.

A227752 a(n) is the number of occurrences of n in A226062.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jul 26 2013

Keywords

Crossrefs

A227753 gives the positions of zeros.

Formula

In the following formula [] stands for Iverson brackets. Essentially we are just naively counting the integers which A226062 maps to n. A000225 is the guaranteed upper limit for the runlength codes for the partitions of size n:
a(n) = Sum_{i=0..A000225(A227183(n))} [A226062(i)==n].
a(n) = Sum_{i=A227368(A227183(n))..A000225(A227183(n))} [A226062(i)==n]. [This is slightly faster if somebody invents a clever formula for the lower limit A227368.]

A322825 A variant of A322827.

Original entry on oeis.org

1, 2, 6, 4, 36, 30, 18, 8, 216, 450, 210, 900, 108, 150, 54, 16, 1296, 6750, 7350, 13500, 44100, 2310, 22050, 27000, 648, 2250, 1470, 4500, 324, 750, 162, 32, 7776, 101250, 257250, 202500, 1543500, 177870, 771750, 405000, 9261000, 2668050, 30030, 5336100, 4630500, 889350, 2315250, 810000, 3888, 33750, 51450, 67500
Offset: 0

Views

Author

Antti Karttunen, Jan 16 2019

Keywords

Crossrefs

Cf. A005811, A227183, A322827 (the main entry).

Programs

  • PARI
    A322825(n) = if(!n,1, my(rl=1, m=1, p=2, eb = (n%2)); n>>=1; while(n,if((n%2)==eb, rl++, eb = 1-eb; m *= p^rl; p = nextprime(1+p)); n >>= 1); m *= p^rl; (m));
    
  • PARI
    A322825(n) = if(!n,1,my(bits = Vecrev(binary(n)), rl=1, o = List([])); for(i=2,#bits,if(bits[i]==bits[i-1], rl++, listput(o,rl))); listput(o,rl); my(es=Vec(o), m=1); for(i=1,#es,m *= prime(i)^es[i]); (m));

Formula

A001221(a(n)) = A005811(n).
A001222(a(n)) = A227183(n).
A046523(a(n)) = A322827(n).
Previous Showing 21-22 of 22 results.