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.

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A121340 List of triples {1^(2^k), 2^(2^k), 3^(2^k)} for k>0.

Original entry on oeis.org

1, 2, 3, 1, 4, 9, 1, 16, 81, 1, 256, 6561, 1, 65536, 43046721, 1, 4294967296, 1853020188851841, 1, 18446744073709551616, 3433683820292512484657849089281, 1, 340282366920938463463374607431768211456, 11790184577738583171520872861412518665678211592275841109096961
Offset: 1

Views

Author

Marius Solend (mariussolend(AT)hotmail.com), Aug 29 2006

Keywords

Crossrefs

Programs

  • Mathematica
    NestList[{#[[ -3]]^2, #[[ -2]]^2, #[[ -1]]^2} &, {1, 2, 3}, 7] // Flatten (* Robert G. Wilson v, Sep 02 2006 *)
    Flatten[Table[{1,2,3}^2^k,{k,0,8}]] (* Harvey P. Dale, May 24 2012 *)

Extensions

More terms from Robert G. Wilson v, Sep 02 2006

A152582 Numbers of the form 9^(2^n) + 2.

Original entry on oeis.org

11, 83, 6563, 43046723, 1853020188851843, 3433683820292512484657849089283, 11790184577738583171520872861412518665678211592275841109096963
Offset: 1

Views

Author

Cino Hilliard, Dec 08 2008

Keywords

Comments

Except for the first term, this sequence is the same as A057727. There appears to be no divisibility rule for this sequence.

Crossrefs

Cf. A059919 (-1), A011764 (-2).

Programs

  • PARI
    g(a,n) = if(a%2,b=2,b=1);for(x=0,n,y=a^(2^x)+b;print1(y","))

A162599 Sum of digits (bits) in base two representation of 3^(2^n).

Original entry on oeis.org

2, 2, 3, 6, 11, 26, 56, 97, 204, 415, 769, 1606, 3268, 6460, 12889, 25915, 52046, 104099, 207000, 416542, 831430, 1662247, 3324374, 6646337, 13292865, 26593542, 53182276, 106364450, 212732814, 425465107, 850887793, 1701801109
Offset: 0

Views

Author

Daniel R. L. Brown, Jul 07 2009

Keywords

Examples

			3^(2^2) = 81 = 64 + 16 + 1, so a(2) = 3.
		

Crossrefs

Cf. A000120, A011764 (3^2^n).

Programs

  • Maple
    a := proc (n) local b2: b2 := convert(3^(2^n), base, 2): add(b2[j], j = 1 .. nops(b2)) end proc: seq(a(n), n = 0 .. 20); # Emeric Deutsch, Jul 21 2009
  • Mathematica
    Table[Total[IntegerDigits[3^2^n,2]],{n,0,25}] (* The program generates the first 26 terms of the seequence. *) (* Harvey P. Dale, Jun 16 2024 *)
  • PARI
    a(n) = hammingweight(3^(2^n)); \\ Michel Marcus, Mar 03 2019

Extensions

Extended by Emeric Deutsch, Jul 21 2009
More terms from Michel Marcus, Mar 03 2019
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