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 1-6 of 6 results.

A323365 Sum of Stern's Diatomic sequence, A002487 and its Dirichlet inverse, A317843.

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 1, 4, 6, 0, 2, 0, 6, 12, 1, 0, 4, 0, 3, 12, 10, 0, 2, 9, 10, 8, 3, 0, -4, 0, 1, 20, 10, 18, 4, 0, 14, 20, 3, 0, 4, 0, 5, 4, 14, 0, 2, 9, 5, 20, 5, 0, 8, 30, 3, 28, 14, 0, 4, 0, 10, 20, 1, 30, -8, 0, 5, 28, 0, 0, 4, 0, 22, -2, 7, 30, 0, 0, 3, 16, 22, 0, 8, 30, 26, 28, 5, 0, 20, 30, 7, 20, 18, 42, 2, 0, 9, 4, 7, 0, 4, 0, 5, 0
Offset: 1

Views

Author

Antti Karttunen, Jan 13 2019

Keywords

Crossrefs

Cf. A002487 (also a quadrisection of this sequence), A317843.

Programs

Formula

a(n) = A002487(n) + A317843(n).
From Antti Karttunen, Dec 08 2021: (Start)
a(1) = 2, and for n > 1, a(n) = -Sum_{d|n, 1A002487(d) * A317843(n/d).
a(4*n) = A002487(n).
(End)

A317839 Möbius transform of A002487, Stern's Diatomic sequence.

Original entry on oeis.org

1, 0, 1, 0, 2, 0, 2, 0, 2, 0, 4, 0, 4, 0, 0, 0, 4, 0, 6, 0, 4, 0, 6, 0, 4, 0, 4, 0, 6, 0, 4, 0, 0, 0, 4, 0, 10, 0, 4, 0, 10, 0, 12, 0, 6, 0, 8, 0, 6, 0, 6, 0, 12, 0, 4, 0, 2, 0, 10, 0, 8, 0, -4, 0, 0, 0, 10, 0, 6, 0, 12, 0, 14, 0, 10, 0, 10, 0, 12, 0, 6, 0, 18, 0, 14, 0, 10, 0, 16, 0, 12, 0, 10, 0, 2, 0, 10, 0, 8, 0, 18, 0, 16, 0, 4
Offset: 1

Views

Author

Antti Karttunen, Aug 09 2018

Keywords

Crossrefs

Programs

  • PARI
    A002487(n) = { my(a=1, b=0); while(n>0, if(bitand(n, 1), b+=a, a+=b); n>>=1); (b); }; \\ From A002487
    A317839(n) = sumdiv(n,d,moebius(n/d)*A002487(d));

Formula

a(n) = Sum_{d|n} A008683(n/d)*A002487(d).
a(n) = A000010(n) - A317841(n).

A317838 a(n) = Sum_{d|n} A002487(d).

Original entry on oeis.org

1, 2, 3, 3, 4, 6, 4, 4, 7, 8, 6, 9, 6, 8, 10, 5, 6, 14, 8, 12, 14, 12, 8, 12, 11, 12, 15, 12, 8, 20, 6, 6, 14, 12, 16, 21, 12, 16, 18, 16, 12, 28, 14, 18, 26, 16, 10, 15, 13, 22, 20, 18, 14, 30, 20, 16, 20, 16, 12, 30, 10, 12, 24, 7, 16, 28, 12, 18, 24, 32, 14, 28, 16, 24, 35, 24, 26, 36, 14, 20, 29, 24, 20, 42, 30, 28, 28, 24
Offset: 1

Views

Author

Antti Karttunen, Aug 09 2018

Keywords

Comments

Inverse Möbius transform of A002487, Stern's Diatomic sequence.

Crossrefs

Programs

  • PARI
    A002487(n) = { my(a=1, b=0); while(n>0, if(bitand(n, 1), b+=a, a+=b); n>>=1); (b); }; \\ From A002487
    A317838(n) = sumdiv(n,d,A002487(d));

Formula

a(n) = Sum_{d|n} A002487(d).
a(n) = A317837(n) + A002487(n).

A317943 Filter sequence constructed from the coefficients of the Stern polynomials B(d,t) collected for each proper divisor d of n; Restricted growth sequence transform of A317942.

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, 25, 26, 2, 27, 28, 29, 2, 30, 2, 31, 32, 33, 2, 34, 35, 36, 37, 38, 2, 39, 40, 41, 42, 43, 2, 44, 2, 45, 46, 47, 48, 49, 2, 50, 51, 52, 2, 53, 2, 54, 55, 56, 57, 58, 2, 59, 60, 61, 2, 62, 63, 64, 65, 66, 2, 67, 68, 69, 70, 71, 72, 73, 2, 74, 75, 76, 2, 77, 2, 78, 79, 80, 2, 81, 2, 82, 83, 84, 2, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 86
Offset: 1

Views

Author

Antti Karttunen, Aug 12 2018

Keywords

Comments

For all i, j: a(i) = a(j) => A317837(i) = A317837(j).

Examples

			Proper divisors of 115 are 1, 5 and 23 and proper divisors of 125 are 1, 5 and 25. The divisors 1 and 5 occur in both, while for the Stern polynomials B(23,t) and B(25,t) (see A125184) the nonzero coefficients are {1, 2, 3, 1} and {1, 3, 2, 1}, that is, they are equal as multisets, thus A286378(23) = A286378(25). From this follows that a(115) = a(125).
		

Crossrefs

Cf. also A293217, A305793.
Differs from A305800 and A296073 for the first time at n=125, where a(125) = 86.

Programs

  • PARI
    \\ Needs also code from A286378:
    up_to = 65537;
    A317942(n) = { my(m=1); fordiv(n,d,if(dA286378(d)-1))); (m); };
    v317943 = rgs_transform(vector(up_to, n, A317942(n)));
    A317943(n) = v317943[n];

A317840 Difference between Stern's Diatomic sequence (A002487) and its Möbius transform (A317839).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Aug 09 2018

Keywords

Crossrefs

Programs

  • PARI
    A002487(n) = { my(a=1, b=0); while(n>0, if(bitand(n, 1), b+=a, a+=b); n>>=1); (b); }; \\ From A002487
    A317840(n) = -sumdiv(n,d,(dA002487(d));

Formula

a(n) = -Sum_{d|n, dA008683(n/d)*A002487(d).
a(n) = A002487(n) - A317839(n).

A319687 a(n) = A318509(n) - A002487(n).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, -2, 0, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, 0, 0, 2, -2, 0, 0, 0, 4, 0, 4, 0, 0, 2, 0, 0, 6, 0, 8, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -2, 0, 0, 0, 2, 0, 0, -2, -6, 0, -4, 0, 0, 0, -4, 0, -6, 0, 10, 0, 0, 0, 4, 2, 0, -2, 0, 0, 0
Offset: 1

Views

Author

Antti Karttunen, Oct 02 2018

Keywords

Comments

All terms seem to be even. See the conjecture given in A261179.

Crossrefs

Programs

  • PARI
    A002487(n) = { my(a=1, b=0); while(n>0, if(bitand(n, 1), b+=a, a+=b); n>>=1); (b); }; \\ From A002487
    A318509(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 1] = A002487(f[i, 1])); factorback(f); };
    A319687(n) = (A318509(n) - A002487(n));
    
  • Python
    from math import prod
    from functools import reduce
    from sympy import factorint
    def A319687(n): return prod(sum(reduce(lambda x,y:(x[0],x[0]+x[1]) if int(y) else (x[0]+x[1],x[1]),bin(p)[-1:2:-1],(1,0)))**e for p, e in factorint(n).items())-sum(reduce(lambda x,y:(x[0],x[0]+x[1]) if int(y) else (x[0]+x[1],x[1]),bin(n)[-1:2:-1],(1,0))) # Chai Wah Wu, May 18 2023

Formula

a(n) = A318509(n) - A002487(n).
Showing 1-6 of 6 results.