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 1-5 of 5 results.

A323914 Lexicographically earliest sequence such that a(i) = a(j) => A322994(i) = A322994(j), for all i, j >= 1.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 5, 3, 6, 2, 5, 2, 7, 4, 8, 2, 9, 2, 8, 6, 10, 2, 8, 3, 11, 5, 12, 2, 13, 2, 12, 7, 14, 4, 8, 2, 15, 10, 12, 2, 16, 2, 17, 5, 18, 2, 12, 3, 19, 11, 20, 2, 21, 6, 17, 14, 22, 2, 8, 2, 23, 8, 17, 7, 24, 2, 25, 15, 26, 2, 12, 2, 27, 9, 28, 4, 29, 2, 17, 8, 30, 2, 12, 10, 31, 18, 20, 2, 21, 6, 32, 22, 33, 11, 17, 2, 34, 12, 12, 2, 35, 2, 25, 13
Offset: 1

Views

Author

Antti Karttunen, Feb 12 2019

Keywords

Comments

Restricted growth sequence transform of A322994.

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; };
    A000265(n) = (n/2^valuation(n, 2));
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A156552(n) = if(1==n, 0, if(!(n%2), 1+(2*A156552(n/2)), 2*A156552(A064989(n))));
    A322993(n) = if(1==n,0,A000265(A156552(n)));
    A322994(n) = sumdiv(n,d,moebius(n/d)*A322993(d));
    v323914 = rgs_transform(vector(up_to,n,A322994(n)));
    A323914(n) = v323914[n];

A322993 a(1) = 0; for n > 1, a(n) = A000265(A156552(n)).

Original entry on oeis.org

0, 1, 1, 3, 1, 5, 1, 7, 3, 9, 1, 11, 1, 17, 5, 15, 1, 13, 1, 19, 9, 33, 1, 23, 3, 65, 7, 35, 1, 21, 1, 31, 17, 129, 5, 27, 1, 257, 33, 39, 1, 37, 1, 67, 11, 513, 1, 47, 3, 25, 65, 131, 1, 29, 9, 71, 129, 1025, 1, 43, 1, 2049, 19, 63, 17, 69, 1, 259, 257, 41, 1, 55, 1, 4097, 13, 515, 5, 133, 1, 79, 15, 8193, 1, 75, 33, 16385, 513, 135, 1, 45, 9
Offset: 1

Views

Author

Antti Karttunen, Jan 02 2019

Keywords

Crossrefs

Cf. A000265, A156552, A246277, A305897 (restricted growth sequence transform), A322994 (Möbius transform).
Cf. also A322995.

Programs

  • Mathematica
    Array[#/2^IntegerExponent[#, 2] &@ Floor@ Total@ Flatten@ MapIndexed[#1 2^(#2 - 1) &, Flatten[Table[2^(PrimePi@ #1 - 1), {#2}] & @@@ FactorInteger@ #]] &, 91] (* Michael De Vlieger, Jan 03 2019 *)
  • PARI
    A000265(n) = (n/2^valuation(n, 2));
    A064989(n) = {my(f); f = factor(n); if((n>1 && f[1,1]==2), f[1,2] = 0); for (i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f)};
    A156552(n) = if(1==n, 0, if(!(n%2), 1+(2*A156552(n/2)), 2*A156552(A064989(n))));
    A322993(n) = if(1==n,0,A000265(A156552(n)));

Formula

a(1) = 0; for n > 1, a(n) = A000265(A156552(n)).
For n > 1, a(n) = A156552(2*A246277(n)).
A000120(a(n)) = A001222(n) for all n >= 1.

A324542 Möbius transform of A324118, where A324118(n) = A000593(A156552(n)).

Original entry on oeis.org

0, 1, 1, 3, 1, 4, 1, 4, 3, 11, 1, 3, 1, 16, 4, 16, 1, 5, 1, 4, 11, 46, 1, 8, 3, 82, 4, 27, 1, 10, 1, 8, 16, 174, 4, 20, 1, 256, 46, 32, 1, 4, 1, 17, 3, 798, 1, 8, 3, 15, 82, 45, 1, 12, 11, 20, 174, 1300, 1, 2, 1, 2734, 4, 72, 16, 27, 1, 125, 256, 8, 1, 20, 1, 4354, 5, 363, 4, 25, 1, 8, 16, 10926, 1, 53, 46, 20518, 798, 168, 1, 35, 11, 317
Offset: 1

Views

Author

Antti Karttunen, Mar 07 2019

Keywords

Comments

The first three zeros after a(1) occur at n = 192, 288, 3645.
The first negative term is a(150) = -1. There are 184 negative terms among the first 4473 terms.

Crossrefs

Programs

Formula

a(n) = Sum_{d|n} A008683(n/d) * A324118(d).

A329373 Dirichlet convolution of the identity function with A322993.

Original entry on oeis.org

0, 1, 1, 5, 1, 10, 1, 17, 6, 16, 1, 40, 1, 26, 13, 49, 1, 49, 1, 66, 19, 46, 1, 124, 8, 80, 25, 108, 1, 114, 1, 129, 31, 148, 17, 185, 1, 278, 49, 206, 1, 182, 1, 192, 65, 538, 1, 340, 10, 111, 85, 330, 1, 190, 25, 336, 151, 1056, 1, 428, 1, 2082, 97, 321, 35, 318, 1, 606, 283, 258, 1, 557, 1, 4136, 87, 1128, 23, 530, 1, 566, 90, 8236, 1, 684, 55, 16430
Offset: 1

Views

Author

Antti Karttunen, Nov 12 2019

Keywords

Comments

Equally, Dirichlet convolution of sigma (A000203) with A322994 (Möbius transform of A322993).

Crossrefs

Programs

  • PARI
    A000265(n) = (n/2^valuation(n, 2));
    A156552(n) = {my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552
    A322993(n) = if(1==n,0,A000265(A156552(n)));
    A329373(n) = sumdiv(n,d,(n/d)*A322993(d));

Formula

a(n) = Sum_{d|n} d * A322993(n/d).
a(n) = Sum_{d|n} A000203(n/d) * A322994(d).

A354185 Möbius transform of A348717.

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 1, 4, 2, 7, 1, 4, 1, 11, 3, 8, 1, 10, 1, 8, 7, 19, 1, 8, 2, 23, 4, 12, 1, 13, 1, 16, 11, 31, 3, 12, 1, 35, 19, 16, 1, 17, 1, 20, 4, 43, 1, 16, 2, 38, 23, 24, 1, 32, 7, 24, 31, 55, 1, 16, 1, 59, 8, 32, 11, 29, 1, 32, 35, 45, 1, 24, 1, 71, 10, 36, 3, 29, 1, 32, 8, 79, 1, 24, 19, 83, 43, 40, 1, 44, 7
Offset: 1

Views

Author

Antti Karttunen, May 19 2022

Keywords

Comments

Question: Are all terms positive?

Crossrefs

Cf. also A322994.

Programs

  • PARI
    A348717(n) = if(1==n, 1, my(f = factor(n), k = primepi(f[1, 1])-1); for (i=1, #f~, f[i, 1] = prime(primepi(f[i, 1])-k)); factorback(f));
    A354185(n) = sumdiv(n,d,moebius(n/d)*A348717(d));

Formula

a(n) = Sum_{d|n} A008683(n/d) * A348717(d).
Showing 1-5 of 5 results.