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 1-4 of 4 results.

A077077 Trajectory of 775 under the Reverse and Add! operation carried out in base 2, written in base 10.

Original entry on oeis.org

775, 1674, 2325, 5022, 8919, 23976, 26757, 47376, 49581, 96048, 102669, 193056, 197469, 388704, 401949, 779328, 788157, 1563840, 1590333, 3131520, 3149181, 6273408, 6326397, 12554496, 12589821, 25129728, 25235709, 50274816, 50345469
Offset: 0

Views

Author

Klaus Brockhaus, Oct 25 2002

Keywords

Comments

The base 2 trajectory of 775 = A075252(5) provably does not contain a palindrome. A proof can be based on the formula given below.
lim_{n -> infinity} a(n)/a(n-1) = 1 for n mod 2 = 1.
lim_{n -> infinity} a(n)/a(n-1) = 2 for n mod 2 = 0.
Interleaving of A177843, 6*A177844, 3*A177845, 6*A177846.

Examples

			775 (decimal) = 1100000111 -> 1100000111 + 1110000011 = 11010001010 = 1674 (decimal).
		

Crossrefs

Cf. A058042 (trajectory of 22 in base 2, written in base 2), A061561 (trajectory of 22 in base 2), A075253 (trajectory of 77 in base 2), A075268 (trajectory of 442 in base 2), A077076 (trajectory of 537 in base 2), A075252 (trajectory of n in base 2 does not reach a palindrome and (presumably) does not join the trajectory of any term m < n).
Cf. A177843 (a(4*n)), A177844 (a(4*n+1)/6), A177845 (a(4*n+2)/3), A177846 (a(4*n+3)/6).

Programs

  • Haskell
    a077077 n = a077077_list !! n
    a077077_list = iterate a055944 775  -- Reinhard Zumkeller, Apr 21 2013
  • Magma
    trajectory:=function(init, steps, base) a:=init; S:=[a]; for n in [1..steps] do a+:= Seqint(Reverse(Intseq(a,base)),base); Append(~S, a); end for; return S; end function; trajectory(775, 28, 2);
    
  • Mathematica
    NestWhileList[# + IntegerReverse[#, 2] &, 775,  # !=
    IntegerReverse[#, 2] &, 1, 28] (* Robert Price, Oct 18 2019 *)
  • PARI
    trajectory(n,steps) = {local(v, k=n); for(j=0, steps, print1(k, ", "); v=binary(k); k+=sum(j=1, #v, 2^(j-1)*v[j]))};
    trajectory(775,28);
    

Formula

a(0), ..., a(5) as above; for n > 5 and
n = 2 (mod 4): a(n) = 3*2^(2*k+7)+273*2^k-3 where k = (n+6)/4;
n = 3 (mod 4): a(n) = 6*2^(2*k+7)-222*2^k where k = (n+5)/4;
n = 0 (mod 4): a(n) = 6*2^(2*k+7)+54*2^k-3 where k = (n+4)/4;
n = 1 (mod 4): a(n) = 12*2^(2*k+7)-282*2^k where k = (n+3)/4.
a(n) = -a(n-1)+2*a(n-2)+2*a(n-3)+2*a(n-4)+2*a(n-5)-4*a(n-6)-4*a(n-7)-3 for n > 12; a(0), ..., a(12) as above.
G.f.: (775+1674*x+1944*x^4+8910*x^5+4650*x^6-14508*x^7-19840*x^8-22644*x^9- 1860*x^10+28680*x^11+14328*x^12-2112*x^13) / ((1-x)*(1+x)*(1-2*x^2)*(1-2*x^4)).
G.f. for the sequence starting at a(6): 3*(8919+15792*x-10230*x^2- 15360*x^3-15358*x^4-31696*x^5+16668*x^6+31264*x^7) / ((1-x)*(1+x)*(1-2*x^2)*(1-2*x^4)).
a(n+1) = A055944(a(n)). - Reinhard Zumkeller, Apr 21 2013

Extensions

Comment edited, three comments and formula added, g.f. edited, PARI program revised, MAGMA program and crossrefs added by Klaus Brockhaus, May 14 2010

A177844 a(n) = 6*a(n-1)-8*a(n-2) for n > 3; a(0)=279, a(1)=3996, a(2)=16008, a(3)=64784.

Original entry on oeis.org

279, 3996, 16008, 64784, 260640, 1045568, 4188288, 16765184, 67084800, 268387328, 1073645568, 4294774784, 17179484160, 68718706688, 274876366848, 1099508547584, 4398040350720, 17592173723648, 70368719536128
Offset: 0

Views

Author

Klaus Brockhaus, May 14 2010

Keywords

Comments

Related to Reverse and Add trajectory of 775 in base 2: a(n) = A077077(4*n+1)/6, i.e. one sixth of second quadrisection of A077077.

Crossrefs

Cf. A077077 (Reverse and Add trajectory of 775 in base 2), A177843, A177845, A177846.

Programs

  • Magma
    [279, 3996] cat [4^(n+5)-47*2^(n+1): n in [2..25]]; // Vincenzo Librandi, Sep 24 2013
  • Mathematica
    CoefficientList[Series[(279 + 2322 x - 5736 x^2 + 704 x^3)/((1 - 2 x) (1 - 4 x)), {x, 0, 40}], x] (* Vincenzo Librandi, Sep 24 2013 *)
  • PARI
    {m=19; v=concat([279, 3996, 16008, 64784], vector(m-4)); for(n=5, m, v[n]=6*v[n-1]-8*v[n-2]); v}
    

Formula

a(n) = 4^(n+5)-47*2^(n+1) for n > 1.
G.f.: (279+2322*x-5736*x^2+704*x^3) / ((1-2*x)*(1-4*x)).
G.f. for the sequence starting at a(2): 8*x^2*(2001-3908*x)/((1-2*x)*(1-4*x)).

A177845 a(n) = 6*a(n-1)-8*a(n-2)-3 for n > 2; a(0)=775, a(1)=8919, a(2)=34223.

Original entry on oeis.org

775, 8919, 34223, 133983, 530111, 2108799, 8411903, 33601023, 134310911, 537057279, 2147856383, 8590680063, 34361229311, 137441935359, 549761777663, 2199035183103, 8796116877311, 35184419799039, 140737583775743
Offset: 0

Views

Author

Klaus Brockhaus, May 14 2010

Keywords

Comments

Related to Reverse and Add trajectory of 775 in base 2: a(n) = A077077(4*n+2)/3, i.e. one third of third quadrisection of A077077.

Crossrefs

Cf. A077077 (Reverse and Add trajectory of 775 in base 2), A177843, A177844, A177846.

Programs

  • Magma
    [775] cat [2*4^(n+5)+91*2^(n+2)-1: n in [1..25]]; // Vincenzo Librandi, Sep 24 2013
  • Mathematica
    nxt[{a_,b_}]:={b,6b-8a-3}; Join[{775},Transpose[NestList[nxt,{8919,34223},20]][[1]]] (* or *) Join[{775},LinearRecurrence[{7,-14,8},{8919,34223,133983},20]] (* Harvey P. Dale, Mar 04 2013 *)
    CoefficientList[Series[(775 + 3494 x - 17360 x^2 + 13088 x^3)/((1 - x) (1 - 2 x) (1 - 4 x)), {x, 0, 40}], x] (* Vincenzo Librandi, Sep 24 2013 *)
  • PARI
    {m=19; v=concat([775, 8919, 34223], vector(m-3)); for(n=4, m, v[n]=6*v[n-1]-8*v[n-2]-3); v}
    

Formula

a(n) = 2*4^(n+5)+91*2^(n+2)-1 for n > 0.
G.f.: (775+3494*x-17360*x^2+13088*x^3) / ((1-x)*(1-2*x)*(1-4*x)).
G.f. for the sequence starting at a(1): x*(8919-28210*x+19288*x^2) / ((1-x)*(1-2*x)*(1-4*x)).
a(0)=775, a(1)=8919, a(2)=34223, a(3)=133983, a(n)=7*a(n-1)-14*a(n-2)+8*a(n-3). - Harvey P. Dale, Mar 04 2013

A177846 a(n) = 6*a(n-1)-8*a(n-2) for n > 2; a(0)=837, a(1)=7896, a(2)=32176.

Original entry on oeis.org

837, 7896, 32176, 129888, 521920, 2092416, 8379136, 33535488, 134179840, 536795136, 2147332096, 8589631488, 34359132160, 137437741056, 549753389056, 2199018405888, 8796083322880, 35184352690176, 140737449558016
Offset: 0

Views

Author

Klaus Brockhaus, May 14 2010

Keywords

Comments

Related to Reverse and Add trajectory of 775 in base 2: a(n) = A077077(4*n+3)/6, i.e. one sixth of fourth quadrisection of A077077.

Crossrefs

Cf. A077077 (Reverse and Add trajectory of 775 in base 2), A177843, A177844, A177845.

Programs

  • Magma
    [837] cat [2*4^(n+5)-37*2^(n+2): n in [1..25]]; // Vincenzo Librandi, Sep 24 2013
  • Mathematica
    CoefficientList[Series[(837 + 2874 x - 8504 x^2)/((1 - 2 x) (1 - 4 x)), {x, 0, 40}], x] (* Vincenzo Librandi, Sep 24 2013 *)
  • PARI
    {m=19; v=concat([837, 7896, 32176], vector(m-3)); for(n=4, m, v[n]=6*v[n-1]-8*v[n-2]); v}
    

Formula

a(n) = 2*4^(n+5)-37*2^(n+2) for n > 0.
G.f.: (837+2874*x-8504*x^2) / ((1-2*x)*(1-4*x)).
G.f. for the sequence starting at a(1): 8*x*(987-1900*x) / ((1-2*x)*(1-4*x)).
Showing 1-4 of 4 results.