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 11-16 of 16 results.

A292250 Binary encoding of 0-digits in ternary representation of A048673(n).

Original entry on oeis.org

0, 0, 1, 0, 0, 0, 1, 0, 0, 2, 0, 0, 3, 0, 3, 0, 2, 2, 1, 4, 6, 2, 1, 0, 0, 0, 3, 0, 0, 0, 2, 0, 5, 6, 1, 4, 1, 4, 0, 8, 0, 14, 1, 4, 12, 0, 7, 0, 4, 2, 1, 0, 5, 8, 2, 0, 4, 2, 4, 0, 4, 6, 5, 0, 5, 8, 3, 12, 2, 4, 2, 8, 0, 4, 1, 8, 3, 2, 1, 16, 16, 2, 3, 28, 0, 0, 1, 8, 0, 26, 8, 0, 9, 0, 15, 0, 1, 10, 14, 4, 0, 4, 7, 0, 4, 12, 6, 16, 5, 6, 8, 0, 2, 10, 9, 4
Offset: 1

Views

Author

Antti Karttunen, Sep 12 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Map[FromDigits[IntegerDigits[#, 3] /. k_ /; k < 3 :> If[k == 0, 1, 0], 2] &, Table[(Times @@ Power[If[# == 1, 1, NextPrime@ #] & /@ First@ #, Last@ #] + 1)/2 &@ Transpose@ FactorInteger@ n, {n, 116}]] (* Michael De Vlieger, Sep 12 2017 *)

Formula

a(n) = A291770(A048673(n)).

A351030 Lexicographically earliest infinite sequence such that a(i) = a(j) => A351031(i) = A351031(j) and A351032(i) = A351032(j), for all i, j >= 1.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 5, 6, 7, 2, 8, 2, 9, 10, 11, 2, 12, 2, 13, 14, 15, 2, 16, 17, 18, 19, 20, 2, 21, 2, 22, 23, 24, 23, 25, 2, 26, 27, 28, 2, 29, 2, 30, 31, 32, 2, 33, 34, 35, 36, 37, 2, 38, 39, 40, 41, 42, 2, 43, 2, 44, 45, 46, 36, 47, 2, 48, 49, 50, 2, 51, 2, 52, 53, 54, 55, 56, 2, 57, 58, 59, 2, 60, 61, 62
Offset: 1

Views

Author

Antti Karttunen, Jan 29 2022

Keywords

Comments

Restricted growth sequence transform of the ordered pair [A351031(n), A351032(n)], or equally, of the ordered pair [A351033(n), A351034(n)].
For all i, j: a(i) = a(j) => A349910(i) = A349910(j).

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; };
    A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };
    A048673(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); (1+factorback(f))/2; };
    A289813(n) = { my(d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==1, 1, 0)), 2); };
    A289814(n) = { my(d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==2, 1, 0)), 2); };
    A291759(n) = A289814(A048673(n));
    A304759(n) = A289813(A048673(n));
    A351031(n) = { my(m=1); fordiv(n,d,if(dA019565(A304759(d)))); (m); };
    A351032(n) = { my(m=1); fordiv(n,d,if(dA019565(A291759(d)))); (m); };
    Aux351030(n) = [A351031(n),A351032(n)];
    v351030 = rgs_transform(vector(up_to, n, Aux351030(n)));
    A351030(n) = v351030[n];

A340377 Numbers k such that there are no 2-digits in the ternary expansion of A048673(k).

Original entry on oeis.org

1, 3, 5, 9, 13, 17, 19, 21, 35, 47, 53, 59, 67, 71, 73, 91, 93, 95, 121, 123, 129, 143, 145, 157, 163, 173, 175, 179, 207, 211, 229, 233, 239, 255, 267, 291, 297, 299, 321, 327, 351, 355, 371, 381, 405, 413, 437, 451, 477, 479, 485, 487, 499, 503, 505, 523, 527, 541, 547, 549, 557, 595, 643, 645, 647, 661, 691, 701
Offset: 1

Views

Author

Antti Karttunen, Jan 15 2021

Keywords

Comments

All terms are odd, because A048673(2n) = 3*A048673(n) - 1, which forces the least significant digit in the ternary expansion of A048673(2n) to be "2".

Crossrefs

Positions of zeros in A291759 and in A340379. Positions of ones in A340382.

Programs

A341345 a(n) = A048673(n) mod 3.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Feb 09 2021

Keywords

Crossrefs

Cf. A007395 (even bisection), A341346 (odd bisection), A341347.
Cf. also A292603.

Programs

  • PARI
    A003961(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); }; \\ From A003961
    A341345(n) = (((A003961(n)+1)/2)%3);

Formula

a(n) = A010872(A048673(n)).
a(n) = 0 iff A292247(n) is odd.
a(n) = 0 iff A292250(n) is odd, or equally, iff both A291759(n) and A304759(n) are even.
a(n) = 0 iff A292251(n) > 0.
a(n) = 1 iff A292248(n) is odd.
a(n) = 1 iff A304759(n) is odd, or equally, iff both A291759(n) and A292250(n) are even.
a(2n) = 2.

A351034 Lexicographically earliest infinite sequence such that a(i) = a(j) => A351032(i) = A351032(j), for all i, j >= 1.

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 3, 1, 2, 1, 4, 1, 5, 1, 6, 1, 7, 1, 6, 8, 5, 1, 9, 1, 2, 1, 10, 1, 11, 1, 12, 8, 2, 8, 9, 1, 2, 1, 13, 1, 14, 1, 11, 15, 5, 1, 16, 8, 17, 1, 11, 1, 18, 8, 19, 1, 5, 1, 20, 1, 21, 8, 13, 1, 22, 1, 6, 8, 10, 1, 23, 1, 21, 24, 4, 25, 22, 1, 26, 27, 21, 1, 28, 1, 29, 8, 30, 1, 31, 8, 10, 15, 2, 1
Offset: 1

Views

Author

Antti Karttunen, Jan 29 2022

Keywords

Comments

Restricted growth sequence transform of A351032.

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; };
    A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };
    A048673(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); (1+factorback(f))/2; };
    A289814(n) = { my(d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==2, 1, 0)), 2); } \\ From A289814
    A291759(n) = A289814(A048673(n));
    A351032(n) = { my(m=1); fordiv(n,d,if(dA019565(A291759(d)))); (m); };
    v351034 = rgs_transform(vector(up_to, n, A351032(n)));
    A351034(n) = v351034[n];

A340379 Number of 2-digits in the ternary representation of A048673(n).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jan 15 2021

Keywords

Comments

Binary weight of A291759(n).

Crossrefs

Cf. A340377 (positions of zeros).

Programs

Formula

a(n) = A081603(A048673(n)) = A000120(A291759(n)).
a(n) = (A286585(n) - A340378(n)) / 2.
For all n >= 1, a(n) >= A292252(n).
Previous Showing 11-16 of 16 results.