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 41-50 of 214 results. Next

A286555 Permutation of natural numbers: a(n) = A252753(A003188(n)).

Original entry on oeis.org

1, 2, 4, 3, 9, 8, 6, 5, 25, 18, 16, 21, 15, 12, 10, 7, 49, 50, 36, 51, 45, 32, 42, 55, 35, 30, 24, 33, 27, 20, 14, 11, 121, 98, 100, 147, 105, 72, 102, 125, 115, 90, 64, 93, 123, 84, 110, 91, 77, 70, 60, 87, 69, 48, 66, 85, 65, 54, 40, 57, 39, 28, 22, 13, 169, 242, 196, 291, 297, 200, 294, 365, 265, 210, 144, 213
Offset: 0

Views

Author

Antti Karttunen, May 13 2017

Keywords

Comments

Note the indexing: the domain starts from 0, but the range from 1.

Crossrefs

Inverse: A286556.
Cf. A286557.
Related or similar permutations: A003188, A252753.

Programs

Formula

a(n) = A252753(A003188(n)).
A046523(a(n)) = A286557(n).

A302784 Inverse permutation to A302783: a(n) = A003188(A052331(n)).

Original entry on oeis.org

0, 1, 3, 6, 12, 2, 24, 7, 48, 13, 96, 5, 192, 25, 15, 384, 768, 49, 1536, 10, 27, 97, 3072, 4, 6144, 193, 51, 30, 12288, 14, 24576, 385, 99, 769, 20, 54, 49152, 1537, 195, 11, 98304, 26, 196608, 102, 60, 3073, 393216, 387, 786432, 6145, 771, 198, 1572864, 50, 108, 31, 1539, 12289, 3145728, 9, 6291456, 24577, 40, 390, 204, 98, 12582912, 774, 3075, 21
Offset: 1

Views

Author

Antti Karttunen, Apr 16 2018

Keywords

Crossrefs

Cf. A302783 (inverse).
Cf. also A302029.

Programs

  • PARI
    up_to = 4096;
    v050376 = vector(up_to);
    ispow2(n) = (n && !bitand(n,n-1));
    i = 0; for(n=1,oo,if(ispow2(isprimepower(n)), i++; v050376[i] = n); if(i == up_to,break));
    A052331(n) = { my(s=0,e); while(n > 1, fordiv(n, d, if(((n/d)>1)&&ispow2(isprimepower(n/d)), e = vecsearch(v050376, n/d); if(!e, print("v050376 too short!"); return(1/0)); s += 2^(e-1); n = d; break))); (s); };
    A003188(n) = bitxor(n, n>>1);
    A302784(n) = A003188(A052331(n));

Formula

a(n) = A003188(A052331(n)).

A322015 If A003188(n+1) < A003188(n), then a(n) = n+1, otherwise a(n) = 0.

Original entry on oeis.org

0, 0, 3, 0, 0, 6, 7, 0, 0, 0, 11, 12, 0, 14, 15, 0, 0, 0, 19, 0, 0, 22, 23, 24, 0, 0, 27, 28, 0, 30, 31, 0, 0, 0, 35, 0, 0, 38, 39, 0, 0, 0, 43, 44, 0, 46, 47, 48, 0, 0, 51, 0, 0, 54, 55, 56, 0, 0, 59, 60, 0, 62, 63, 0, 0, 0, 67, 0, 0, 70, 71, 0, 0, 0, 75, 76, 0, 78, 79, 0, 0, 0, 83, 0, 0, 86, 87, 88, 0, 0, 91, 92, 0, 94, 95, 96
Offset: 0

Views

Author

Antti Karttunen, Nov 24 2018

Keywords

Crossrefs

Programs

A322016 a(0) = 0; for n > 0, if A003188(n) > A003188(n-1) then a(n) = n-1, otherwise a(n) = 0.

Original entry on oeis.org

0, 0, 1, 0, 3, 4, 0, 0, 7, 8, 9, 0, 0, 12, 0, 0, 15, 16, 17, 0, 19, 20, 0, 0, 0, 24, 25, 0, 0, 28, 0, 0, 31, 32, 33, 0, 35, 36, 0, 0, 39, 40, 41, 0, 0, 44, 0, 0, 0, 48, 49, 0, 51, 52, 0, 0, 0, 56, 57, 0, 0, 60, 0, 0, 63, 64, 65, 0, 67, 68, 0, 0, 71, 72, 73, 0, 0, 76, 0, 0, 79, 80, 81, 0, 83, 84, 0, 0, 0, 88, 89, 0, 0, 92, 0, 0, 0, 96, 97
Offset: 0

Views

Author

Antti Karttunen, Nov 24 2018

Keywords

Crossrefs

Programs

Formula

a(0) = 0; for n > 0, a(n) = (1/2)*(A034947(n)+1)*(n-1).

A099892 XOR BINOMIAL transform of A003188 (Gray code numbers); also the main diagonal of the XOR difference triangle A099891.

Original entry on oeis.org

0, 1, 3, 0, 6, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0, 24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 48, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 96, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Paul D. Hanna, Oct 29 2004

Keywords

Comments

See A099884 for the definitions of the XOR BINOMIAL transform and the XOR difference triangle.

Crossrefs

Programs

  • Mathematica
    a[n_] := Module[{e = IntegerExponent[n, 2]}, Switch[n, 0, 0, 1, 1, 2^e, 3*2^(e - 1), , 0]]; Array[a, 100, 0] (* _Amiram Eldar, Aug 31 2023, corrected by Michael Shamos, May 22 2025 *)
  • PARI
    {a(n)=local(B);B=0;for(i=0,n,B=bitxor(B,binomial(n,i)%2*(bitxor((n-i),(n-i)\2))));B}

Formula

a(2^n) = 3*2^(n-1) for n>0, with a(0)=0, a(1) = 1 and a(k)=0 otherwise. a(n) = SumXOR_{i=0..n} (C(n, i)mod 2)*A003188(n-i), where A003188(k)=bitxor(k, [k/2]) and SumXOR is summation under XOR.
Multiplicative with a(2^e) = 3*2^(e-1), a(p^e) = 0 otherwise. - David W. Wilson, Jun 12 2005
Dirichlet g.f.: (2^s+1)/(2^s-2). - R. J. Mathar, Apr 14 2011

A227526 G.f.: Sum_{n>=0} x^n * (1+x)^A003188(n), where A003188(n) = n XOR [n/2] is the Gray code for n.

Original entry on oeis.org

1, 1, 2, 4, 6, 9, 23, 47, 65, 70, 111, 323, 902, 2064, 3997, 6697, 9638, 11664, 11804, 11436, 18903, 61053, 209236, 623648, 1610326, 3685365, 7673031, 14926689, 27784642, 50202979, 88022528, 147757232, 232939294, 338735927, 448199945, 534600063, 571408283, 546281026, 475461610
Offset: 0

Views

Author

Paul D. Hanna, Jul 14 2013

Keywords

Comments

A(-1/2) = Sum_{n>=0} (-1)^n / 2^(n + A003188(n)) = 0.75073331594540770872470210...

Examples

			G.f.: A(x) = 1 + x + 2*x^2 + 4*x^3 + 6*x^4 + 9*x^5 + 23*x^6 + 47*x^7 + 65*x^8 +...
where
A(x) = 1 + x*(1+x) + x^2*(1+x)^3 + x^3*(1+x)^2 + x^4*(1+x)^6 + x^5*(1+x)^7 + x^6*(1+x)^5 + x^7*(1+x)^4 + x^8*(1+x)^12 + x^9*(1+x)^13 + x^10*(1+x)^15 + x^11*(1+x)^14 + x^12*(1+x)^10 + x^13*(1+x)^11 + x^14*(1+x)^9 + x^15*(1+x)^8 +...
		

Crossrefs

Programs

  • PARI
    {a(n)=polcoeff(sum(m=0, n, x^m*(1+x+x*O(x^n))^bitxor(m,m\2)), n)}
    for(n=0, 64, print1(a(n), ", "))
    
  • PARI
    {a(n) = sum(k=0, n, binomial(bitxor(k,k\2), n-k))}
    for(n=0, 64, print1(a(n), ", "))

Formula

a(n) = Sum_{k=0..n} binomial(A003188(k), n-k), where A003188(k) = k XOR [k/2].

A227527 G.f.: Sum_{n>=0} x^n * (1-x)^A003188(n), where A003188(n) = n XOR [n/2] is the Gray code for n.

Original entry on oeis.org

1, 1, 0, -2, 2, -5, 9, -3, -13, 14, 35, -149, 300, -450, 673, -1151, 1856, -2366, 2424, -3192, 9319, -32687, 96858, -238410, 508290, -998065, 1925065, -3750685, 7162328, -12635545, 19437562, -24482990, 22154946, -6283107, -25823457, 69598597, -113006459, 140737910, -137007218, 67953174
Offset: 0

Views

Author

Paul D. Hanna, Jul 14 2013

Keywords

Comments

A(1/2) = Sum_{n>=0} 1/2^(n + A003188(n)) = 1.3146990537656455533266364007421...

Examples

			G.f.: A(x) = 1 + x - 2*x^3 + 2*x^4 - 5*x^5 + 9*x^6 - 3*x^7 - 13*x^8 + 14*x^9 +...
where A(x) = A(1-x) equals the series:
A(x) = 1 + x*(1-x) + x^2*(1-x)^3 + x^3*(1-x)^2 + x^4*(1-x)^6 + x^5*(1-x)^7 + x^6*(1-x)^5 + x^7*(1-x)^4 + x^8*(1-x)^12 + x^9*(1-x)^13 + x^10*(1-x)^15 + x^11*(1-x)^14 + x^12*(1-x)^10 + x^13*(1-x)^11 + x^14*(1-x)^9 + x^15*(1-x)^8 +...
		

Crossrefs

Programs

  • PARI
    {a(n)=polcoeff(sum(m=0, n, x^m*(1-x+x*O(x^n))^bitxor(m,m\2)), n)}
    for(n=0, 64, print1(a(n), ", "))
    
  • PARI
    {a(n) = sum(k=0, n, (-1)^(n-k)*binomial(bitxor(k,k\2), n-k))}
    for(n=0, 64, print1(a(n), ", "))

Formula

a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(A003188(k), n-k), where A003188(k) = k XOR [k/2].

A268722 a(n) = A003188(3*A006068(n)), where A003188 is binary Gray code and A006068 is its inverse.

Original entry on oeis.org

0, 2, 13, 5, 31, 27, 10, 8, 59, 63, 54, 52, 20, 22, 49, 17, 115, 119, 126, 124, 108, 110, 121, 105, 40, 42, 37, 45, 103, 99, 34, 32, 227, 231, 238, 236, 252, 254, 233, 249, 216, 218, 213, 221, 247, 243, 210, 208, 80, 82, 93, 85, 79, 75, 90, 88, 203, 207, 198, 196, 68, 70, 193, 65
Offset: 0

Views

Author

Antti Karttunen, Feb 13 2016

Keywords

Crossrefs

Row 2 and column 2 of array A268725.

Programs

Formula

a(n) = A003188(3*A006068(n)).

A268723 Main diagonal of A268725: a(n) = A003188(A006068(n)^2), where A003188 is binary Gray code and A006068 is its inverse.

Original entry on oeis.org

0, 1, 13, 6, 41, 54, 24, 21, 145, 166, 216, 253, 96, 121, 69, 86, 545, 582, 664, 749, 864, 841, 949, 1014, 384, 433, 477, 486, 793, 278, 344, 357, 2113, 2182, 2328, 2509, 2656, 2793, 2901, 2998, 3456, 3537, 3901, 3366, 3641, 3798, 4056, 3973, 1536, 1633, 1709, 1734, 1801, 1910, 1944, 2037, 3313, 3174, 1112, 1053
Offset: 0

Views

Author

Antti Karttunen, Feb 13 2016

Keywords

Crossrefs

Main diagonal of array A268725.

Programs

Formula

a(n) = A003188(A000290(A006068(n))).

A286383 a(n) = A278233(A003188(n)).

Original entry on oeis.org

1, 2, 2, 6, 2, 4, 4, 12, 2, 8, 6, 12, 2, 6, 8, 24, 2, 12, 6, 24, 2, 6, 12, 36, 4, 6, 6, 30, 2, 16, 16, 48, 6, 32, 6, 60, 2, 6, 12, 72, 2, 12, 6, 30, 2, 12, 24, 72, 2, 6, 12, 30, 2, 24, 12, 60, 2, 12, 6, 48, 6, 6, 32, 96, 2, 12, 30, 96, 2, 30, 12, 180, 2, 6, 6, 30, 8, 24, 24, 216, 6, 6, 6, 60, 6, 12, 12, 60, 2, 48, 6, 60, 2, 6, 48, 144, 4, 30, 6, 30, 2, 64, 36
Offset: 1

Views

Author

Antti Karttunen, May 08 2017

Keywords

Crossrefs

Programs

Formula

a(n) = A278233(A003188(n)).
Previous Showing 41-50 of 214 results. Next