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 1-2 of 2 results.

A064301 Rightmost column of A064744; 2-adic valuation of the EKG-sequence.

Original entry on oeis.org

0, 1, 2, 1, 0, 0, 2, 3, 1, 0, 0, 1, 1, 0, 0, 3, 4, 2, 1, 0, 0, 0, 1, 0, 0, 2, 1, 0, 0, 2, 5, 1, 0, 0, 1, 1, 0, 0, 0, 3, 2, 1, 0, 0, 4, 1, 2, 1, 3, 0, 0, 2, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 3, 6, 2, 1, 0, 0, 0, 1, 2, 4, 1, 0, 0, 0, 2, 0, 3, 1, 0, 0, 1, 0, 0, 2, 2, 1, 0, 0, 5, 1, 0, 3, 1, 0, 0, 2, 1, 0, 0, 1, 1, 4, 2
Offset: 1

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Author

N. J. A. Sloane, Oct 20 2001

Keywords

Comments

Exponent of highest power of 2 dividing A064413(n).

Crossrefs

Programs

  • Mathematica
    IntegerExponent[#, 2] & /@ Nest[Append[#, Block[{k = 3}, While[Or[MemberQ[#, k], GCD[#[[-1]], k] == 1], k++]; k]] &, {1, 2}, 105] (* Michael De Vlieger, May 22 2018 *)
  • PARI
    A064301(n) = valuation(A064413(n),2); \\ Needs also code from A064413. - Antti Karttunen, May 18 2018

Extensions

More terms from Vladeta Jovovic, Oct 21 2001
An alternative description added to name by Antti Karttunen, May 18 2018

A304738 Restricted growth sequence transform of A278222(A048673(n)).

Original entry on oeis.org

1, 1, 2, 3, 1, 1, 2, 4, 5, 5, 4, 6, 3, 3, 3, 7, 3, 5, 2, 1, 4, 3, 8, 3, 5, 5, 9, 5, 1, 10, 5, 11, 3, 6, 6, 6, 7, 5, 10, 12, 5, 10, 2, 13, 5, 5, 14, 15, 11, 7, 2, 10, 8, 11, 6, 16, 6, 11, 17, 11, 3, 4, 7, 18, 8, 5, 3, 10, 7, 6, 7, 16, 3, 17, 19, 5, 3, 1, 7, 6, 20, 3, 10, 17, 5, 6, 6, 5, 5, 6, 11, 5, 20, 3, 7, 5, 14, 15, 10, 21, 5, 11, 14, 13, 5
Offset: 1

Views

Author

Antti Karttunen, May 18 2018

Keywords

Comments

Sequence allots a distinct value for each distinct multiset formed from the lengths of 1-runs in the binary representation of A048673(n). Compare to the scatter plot of A286622.

Crossrefs

Programs

  • PARI
    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
    A278222(n) = A046523(A005940(1+n));
    A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From A003961
    A048673(n) = (A003961(n)+1)/2;
    v304738 = rgs_transform(vector(65539,n,A278222(A048673(n))));
    A304738(n) = v304738[n];
Showing 1-2 of 2 results.