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 1-5 of 5 results.

A005009 a(n) = 7*2^n.

Original entry on oeis.org

7, 14, 28, 56, 112, 224, 448, 896, 1792, 3584, 7168, 14336, 28672, 57344, 114688, 229376, 458752, 917504, 1835008, 3670016, 7340032, 14680064, 29360128, 58720256, 117440512, 234881024, 469762048, 939524096, 1879048192, 3758096384
Offset: 0

Views

Author

Keywords

Comments

The first differences are the sequence itself. - Alexandre Wajnberg & Eric Angelini, Sep 07 2005

Crossrefs

Sequences of the form (2*m+1)*2^n: A000079 (m=0), A007283 (m=1), A020714 (m=2), this sequence (m=3), A005010 (m=4), A005015 (m=5), A005029 (m=6), A110286 (m=7), A110287 (m=8), A110288 (m=9), A175805 (m=10), A248646 (m=11), A164161 (m=12), A175806 (m=13), A257548 (m=15).
Row sums of (6, 1)-Pascal triangle A093563 and of (1, 6)-Pascal triangle A096956, n>=1.

Programs

Formula

G.f.: 7/(1-2*x).
a(n) = A118416(n+1,4) for n > 3. - Reinhard Zumkeller, Apr 27 2006
a(n) = 2*a(n-1), for n > 0, with a(0)=7 . - Philippe Deléham, Nov 23 2008
a(n) = 7 * A000079(n). - Omar E. Pol, Dec 16 2008
a(n) = A173787(n+3,n). - Reinhard Zumkeller, Feb 28 2010
Intersection of A014311 and A212191: all terms and their squares are the sum of exactly three distinct powers of 2, A000120(a(n)) = A000120(a(n)^2) = 3. - Reinhard Zumkeller, May 03 2012
G.f.: 2/x/G(0) - 1/x + 9, where G(k)= 1 + 1/(1 - x*(7*k+2)/(x*(7*k+9) + 1/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, Jun 03 2013
E.g.f.: 7*exp(2*x). - Stefano Spezia, May 15 2021

A091629 Product of digits associated with A091628(n). Essentially the same as A007283.

Original entry on oeis.org

6, 12, 24, 48, 96, 192, 384, 768, 1536, 3072, 6144, 12288, 24576, 49152, 98304, 196608, 393216, 786432, 1572864, 3145728, 6291456, 12582912, 25165824, 50331648, 100663296, 201326592, 402653184, 805306368, 1610612736, 3221225472
Offset: 1

Views

Author

Enoch Haga, Jan 24 2004

Keywords

Comments

Sequence arising in Farideh Firoozbakht's solution to Prime Puzzle 251 - 23 is the only pointer prime (A089823) not containing digit "1".
The monotonic increasing value of successive product of digits strongly suggests that in successive n the digit 1 must be present.

Crossrefs

Sequences of the form (2*m+1)*2^n: A000079 (m=0), A007283 (m=1), A020714 (m=2), A005009 (m=3), A005010 (m=4), A005015 (m=5), A005029 (m=6), A110286 (m=7), A110287 (m=8), A110288 (m=9), A175805 (m=10), A248646 (m=11), A164161 (m=12), A175806 (m=13), A257548 (m=15).

Programs

Formula

a(n) = 3 * 2^n = product of digits of A091628(n).
From Philippe Deléham, Nov 23 2008: (Start)
a(n) = 6*2^(n-1).
a(n) = 2*a(n-1), with a(1) = 6.
G.f.: 6*x/(1-2*x). (End)
E.g.f.: 3*(exp(2*x) - 1). - G. C. Greubel, Jan 05 2023

Extensions

Edited and extended by Ray Chandler, Feb 07 2004

A110287 a(n) = 17*2^n.

Original entry on oeis.org

17, 34, 68, 136, 272, 544, 1088, 2176, 4352, 8704, 17408, 34816, 69632, 139264, 278528, 557056, 1114112, 2228224, 4456448, 8912896, 17825792, 35651584, 71303168, 142606336, 285212672, 570425344, 1140850688, 2281701376, 4563402752, 9126805504, 18253611008
Offset: 0

Views

Author

Alexandre Wajnberg, Sep 07 2005

Keywords

Comments

The first differences are the sequence itself. Doubling the terms gives the same sequence (beginning one step further).
17 times powers of 2. - Omar E. Pol, Dec 17 2008

Crossrefs

Sequences of the form (2*m+1)*2^n: A000079 (m=0), A003945 (m=1), A020714 (m=2), A005009 (m=3), A005010 (m=4), A005015 (m=5), A005029 (m=6), A110286 (m=7), this sequence (m=8), A110288 (m=9), A175805 (m=10), A248646 (m=11), A164161 (m=12), A175806 (m=13), A257548 (m=15).
Cf. A007283.

Programs

Formula

G.f.: 17/(1-2*x). - Philippe Deléham, Nov 23 2008
a(n) = 17*A000079(n). - Omar E. Pol, Dec 17 2008
a(n) = 2*a(n-1) (with a(0)=17). - Vincenzo Librandi, Dec 26 2010
a(n) = A173786(n+4, n) for n>3. - Reinhard Zumkeller, Feb 28 2010
E.g.f.: 17*exp(2*x). - G. C. Greubel, Jan 05 2023

Extensions

Edited by Omar E. Pol, Dec 16 2008

A198276 a(n) = 19*2^n-1.

Original entry on oeis.org

18, 37, 75, 151, 303, 607, 1215, 2431, 4863, 9727, 19455, 38911, 77823, 155647, 311295, 622591, 1245183, 2490367, 4980735, 9961471, 19922943, 39845887, 79691775, 159383551, 318767103, 637534207, 1275068415, 2550136831, 5100273663, 10200547327, 20401094655
Offset: 0

Views

Author

Jeremy Gardiner, Oct 23 2011

Keywords

Examples

			a(2) = 19*2^2-1 = 75.
		

Crossrefs

Programs

  • BASIC
    for j = 0 to 30 : print str$((19*2^j)-1)+", "; : next j
    
  • Magma
    [19*2^n-1: n in [0..30]]; // Vincenzo Librandi, Oct 28 2011
  • Maple
    A198276:=n->19*2^n-1; seq(A198276(n), n=0..30); # Wesley Ivan Hurt, Jun 11 2014
  • Mathematica
    19*2^Range[0,30]-1 (* or *) LinearRecurrence[{3,-2},{18,37},40] (* Harvey P. Dale, Dec 18 2013 *)

Formula

a(n+1) = 2*a(n) + 1.
G.f.: ( 18-17*x ) / ( (2*x-1)*(x-1) ). - R. J. Mathar, Oct 25 2011
a(n) + a(n-1)^2 = (a(n-1)+1)^2. - Vincenzo Librandi, Jun 11 2014

A159027 a(0)=109; a(n) = a(n-1) + floor(sqrt(a(n-1))), n > 0.

Original entry on oeis.org

109, 119, 129, 140, 151, 163, 175, 188, 201, 215, 229, 244, 259, 275, 291, 308, 325, 343, 361, 380, 399, 418, 438, 458, 479, 500, 522, 544, 567, 590, 614, 638, 663, 688, 714, 740, 767, 794, 822, 850, 879, 908, 938, 968, 999, 1030, 1062, 1094, 1127, 1160, 1194, 1228, 1263, 1298, 1334, 1370, 1407, 1444
Offset: 0

Views

Author

Philippe Deléham, Apr 02 2009

Keywords

Comments

Row 9 in square array A159016.
This sequence contains infinitely many squares. - Philippe Deléham, Apr 04 2009

Crossrefs

Programs

  • Mathematica
    NestList[#+Floor[Sqrt[#]]&,109,60] (* Harvey P. Dale, May 01 2020 *)

Extensions

More terms from Vincenzo Librandi, Apr 10 2009
Showing 1-5 of 5 results.