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 1-2 of 2 results.

A245594 Numbers k that divide 2^k + 10.

Original entry on oeis.org

1, 2, 3, 9, 14, 161, 261, 5727, 12127, 16394, 20029238, 577738261, 2637324098, 45019843643, 54756012358, 142046769201, 2144325306742, 2247950127743, 34462584090334, 223385072880447
Offset: 1

Views

Author

Derek Orr, Jul 27 2014

Keywords

Comments

No other terms below 10^15. Some larger terms: 58431276133663538, 107614684491896498, 246944720684027923581501, 2^260+5 (79 digits), 581*p (112 digits) where p is the largest prime factor of 2^580+5. - Max Alekseyev, Oct 01 2016

Examples

			3 divides 2^3 + 10 = 18. Thus 3 is a term of this sequence.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[10^5], Divisible[2^# + 10, #] &] (* Robert Price, Oct 12 2018 *)
  • PARI
    for(n=1,10^9,if(Mod(2,n)^n==Mod(-10,n),print1(n,", ")))

Extensions

a(13)-a(20) from Max Alekseyev, Oct 01 2016

A267615 a(n) = 2^n + 11.

Original entry on oeis.org

12, 13, 15, 19, 27, 43, 75, 139, 267, 523, 1035, 2059, 4107, 8203, 16395, 32779, 65547, 131083, 262155, 524299, 1048587, 2097163, 4194315, 8388619, 16777227, 33554443, 67108875, 134217739, 268435467, 536870923, 1073741835, 2147483659, 4294967307, 8589934603, 17179869195, 34359738379
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 18 2016

Keywords

Comments

Recurrence relation b(n) = 3*b(n - 1) - 2*b(n - 2) for n>1, b(0) = k, b(1) = k + 1, gives the closed form b(n) = 2^n + k - 1.

Crossrefs

Cf. sequences with closed form 2^n + k - 1: A168616 (k=-4), A028399 (k=-3), A036563 (k=-2), A000918 (k=-1), A000225 (k=0), A000079 (k=1), A000051 (k=2), A052548 (k=3), A062709 (k=4), A140504 (k=5), A168614 (k=6), A153972 (k=7), A168415 (k=8), A242475 (k=9), A188165 (k=10), A246139 (k=11), this sequence (k=12).
Cf. A156940.

Programs

  • Magma
    [2^n+11: n in [0..30]]; // Vincenzo Librandi, Jan 19 2016
  • Mathematica
    Table[2^n + 11, {n, 0, 35}]
    LinearRecurrence[{3, -2}, {12, 13}, 40] (* Vincenzo Librandi, Jan 19 2016 *)
  • PARI
    a(n) = 2^n + 11; \\ Altug Alkan, Jan 18 2016
    

Formula

G.f.: (12 - 23*x)/(1 - 3*x + 2*x^2).
a(n) = 3*a(n - 1) - 2*a(n - 2) for n>1, a(0)=12, a(1)=13.
a(n) = A000079(n) + A010850(n).
Sum_{n>=0} 1/a(n) = 0.367971714327125...
Lim_{n->oo} a(n + 1)/a(n) = 2.
E.g.f.: exp(2*x) + 11*exp(x). - Elmo R. Oliveira, Nov 08 2023
Showing 1-2 of 2 results.