A007395 -id:A007395 - cp's OEIS frontend

A010693 Periodic sequence: Repeat 2,3.

2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3

Offset: 0

N. J. A. Sloane

a(n) = smallest prime divisor of n!! for n >= 2. For biggest prime divisor of n!! see A139421. - Artur Jasinski, Apr 21 2008
Let A be the Hessenberg matrix of order n, defined by: A[1,j]=1, A[i,i]:=-3, A[i,i-1]=-1, and A[i,j]=0 otherwise. Then, for n>=1, a(n)=-charpoly(A,-2). - Milan Janjic, Jan 27 2010
Simple continued fraction of 1+sqrt(5/3) = A176020. - R. J. Mathar, Mar 08 2012
p(n) = a(n-1) is the Abelian complexity function of the Thue-Morse word A010060. - Nathan Fox, Mar 12 2013

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 466
G. Richomme, K. Saari, and L. Q. Zamboni, Abelian complexity in minimal subshifts, J. London Math. Soc. 83(1) (2011) 79-95.
G. Richomme, K. Saari, and L. Q. Zamboni, Abelian complexity in minimal subshifts, arXiv:0911.2914 [math.CO], 2009.
Index entries for linear recurrences with constant coefficients, signature (0,1).

Cf. A139421.

Cf. A026549 (partial products).

a010693 = (+ 2) . (`mod` 2)  -- Reinhard Zumkeller, Nov 27 2012
a010693_list = cycle [2,3]  -- Reinhard Zumkeller, Mar 29 2012

[2 + (n mod 2) : n in [0..100]]; // Wesley Ivan Hurt, Jul 24 2014

A010693:=n->2+(n mod 2): seq(A010693(n), n=0..100); # Wesley Ivan Hurt, Jul 24 2014

Table[5/2 - (-1)^n/2, {n, 0, 100}] or a = {}; Do[b = First[First[FactorInteger[n!! ]]]; AppendTo[a, b], {n, 2, 1000}]; a (* Artur Jasinski, Apr 21 2008 *)
2 + Mod[Range[0, 100], 2] (* Wesley Ivan Hurt, Jul 24 2014 *)
PadRight[{},120,{2,3}] (* Harvey P. Dale, Jan 20 2023 *)

a(n)=3 - (n+1)%2 \\ Charles R Greathouse IV, May 09 2016

a(n) = 5/2 - ((-1)^n)/2.
a(n) = 2 + (n mod 2) = A007395(n) + A000035(n). - Reinhard Zumkeller, Mar 23 2005
a(n) = A020639(A016767(n)) for n>0. - Reinhard Zumkeller, Jan 29 2009
From Jaume Oliver Lafont, Mar 20 2009: (Start)
G.f.: (2+3*x)/(1-x^2).
Linear recurrence: a(0)=2, a(1)=3, a(n)=a(n-2) for n>=2. (End)
a(n) = A001615(2n)/A001615(n) for n > 0. - Enrique Pérez Herrero, Jun 06 2012
a(n) = floor((n+1)*5/2) - floor((n)*5/2). - Hailey R. Olafson, Jul 23 2014
a(n) = 3 - ((n+1) mod 2). - Wesley Ivan Hurt, Jul 24 2014
E.g.f.: 2*cosh(x) + 3*sinh(x). - Stefano Spezia, Aug 04 2025

Definition rewritten by Bruno Berselli, Sep 30 2011

A182406 Square array A(n,k), n>=1, k>=1, read by antidiagonals: A(n,k) is the number of n-colorings of the square grid graph G_(k,k).

Original entry on oeis.org

1, 0, 2, 0, 2, 3, 0, 2, 18, 4, 0, 2, 246, 84, 5, 0, 2, 7812, 9612, 260, 6, 0, 2, 580986, 6000732, 142820, 630, 7, 0, 2, 101596896, 20442892764, 828850160, 1166910, 1302, 8, 0, 2, 41869995708, 380053267505964, 50820390410180, 38128724910, 6464682, 2408, 9

Offset: 1

Alois P. Heinz, Apr 27 2012

The square grid graph G_(n,n) has n^2 = A000290(n) vertices and 2*n*(n-1) = A046092(n-1) edges. The chromatic polynomial of G_(n,n) has n^2+1 = A002522(n) coefficients.

			Square array A(n,k) begins:
  1,   0,       0,           0,                 0, ...
  2,   2,       2,           2,                 2, ...
  3,  18,     246,        7812,            580986, ...
  4,  84,    9612,     6000732,       20442892764, ...
  5, 260,  142820,   828850160,    50820390410180, ...
  6, 630, 1166910, 38128724910, 21977869327169310, ...

Eric Weisstein's World of Mathematics, Grid Graph
Wikipedia, Chromatic Polynomial

Columns k=1-7 give: A000027, A091940, A068239*2, A068240*2, A068241*2, A068242*2, A068243*2.
Rows n=1-20 give: A000007, A007395, A068253*3, A068254*4, A068255*5, A068256*6, A068257*7, A068258*8, A068259*9, A068260*10, A068261*11, A068262*12, A068263*13, A068264*14, A068265*15, A068266*16, A068267*17, A068268*18, A068269*19, A068270*20.
Cf. A182368.

A000038 Twice A000007.

Original entry on oeis.org

2, 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, 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, 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, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 0

N. J. A. Sloane

Multiplicative with a(p^e) = 0. - Mitch Harris, Jun 09 2005

Also decimal expansion of 1/5, with keyword cons. - Wolfdieter Lang, Jan 19 2023

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

James Spahlinger, Table of n, a(n) for n = 0..10000
Norman L. de Forest, The Square Root of 4 to a Million Places, Project Gutenberg EBook 3651, 2003.
Daniele A. Gewurz and Francesca Merola, Sequences realized as Parker vectors of oligomorphic permutation groups, J. Integer Seqs., Vol. 6, 2003.
Chai Wah Wu, Can machine learning identify interesting mathematics? An exploration using empirically observed laws, arXiv:1805.07431 [cs.LG], 2018.
Dominika Závacká, Cristina Dalfó, and Miquel Angel Fiol, Integer sequences from k-iterated line digraphs, CEUR: Proc. 24th Conf. Info. Tech. - Appl. and Theory (ITAT 2024) Vol 3792, 156-161. See p. 161, Table 2. See p. 6.

Cf. A007395, A000007.

a000038 n = 2 * a000007 n -- James Spahlinger, Oct 08 2012

PadRight[{2}, 104] (* or *)
Array[(-1)^Prime@ # + 1 &, 105] (* Michael De Vlieger, Aug 15 2018 *)

a(n)=if(n,0,2) \\ Charles R Greathouse IV, Oct 09 2012

a(n) = 2*A000007(n) = (-1)^A000040(n) + 1. - Juri-Stepan Gerasimov, Oct 29 2009

A010709 Constant sequence: the all 4's sequence.

Original entry on oeis.org

4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4

Offset: 0

N. J. A. Sloane

From Klaus Brockhaus, May 25 2010: (Start)
Continued fraction expansion of 2+sqrt(5).
Decimal expansion of 4/9.
Inverse binomial transform of A020707. (End)

Tom Edgar, Proof without words: sum of powers of 4/9, Math. Mag. 89 no. 3 (2016) 191.
Tanya Khovanova, Recursive Sequences
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1012
Dominika Závacká, Cristina Dalfó, and Miquel Angel Fiol, Integer sequences from k-iterated line digraphs, CEUR: Proc. 24th Conf. Info. Tech. - Appl. and Theory (ITAT 2024) Vol 3792, 156-161. See p. 161, Table 2.
Index to divisibility sequences
Index entries for linear recurrences with constant coefficients, signature (1).

From Klaus Brockhaus, May 25 2010: (Start)
Equals 4*A000012, 2*A007395, A010731/2, A010855/4, A010871/8.
Cf. A098317 (decimal expansion of 2+sqrt(5)), A020707 (2^(n+2)). (End)

makelist(4, n, 0, 30); /* Martin Ettl, Nov 09 2012 */

a(n) = 4 \\ Charles R Greathouse IV, Apr 07 2012

def A010709(n): return 4 # Chai Wah Wu, Mar 22 2023

From Klaus Brockhaus, May 25 2010: (Start)
a(n) = 4.
G.f.: 4/(1-x). (End)
E.g.f.: 4*e^x. - Vincenzo Librandi, Jan 29 2012

A034524 a(n) = 11^n + 1.

Original entry on oeis.org

2, 12, 122, 1332, 14642, 161052, 1771562, 19487172, 214358882, 2357947692, 25937424602, 285311670612, 3138428376722, 34522712143932, 379749833583242, 4177248169415652, 45949729863572162, 505447028499293772

Offset: 0

N. J. A. Sloane

T. D. Noe, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (12,-11).

Sequences of the form m^n + 1: A000012 (m=0), A007395 (m=1), A000051 (m=2), A034472 (m=3), A052539 (m=4), A034474 (m=5), A062394 (m=6), A034491 (m=7), A062395 (m=8), A062396 (m=9), A062397 (m=10), this sequence (m=11), A178248 (m=12), A141012 (m=13), A228081 (m=64).

Cf. A001020.

[11^n +1: n in [0..30]]; // G. C. Greubel, Mar 11 2023

LinearRecurrence[{12,-11},{2,12},18] (* Ray Chandler, Aug 26 2015 *)
11^Range[0,30]+1 (* G. C. Greubel, Mar 11 2023 *)

a(n)=11^n+1 \\ Charles R Greathouse IV, Sep 24 2015

[sigma(11,n)for n in range(0,18)] # - Zerinvary Lajos, Jun 04 2009

From Mohammad K. Azarian, Jan 02 2009: (Start)
G.f.: 1/(1-x) + 1/(1-11*x).
E.g.f.: exp(x) + exp(11*x). (End)
From G. C. Greubel, Mar 11 2023: (Start)
a(n) = 11*a(n-1) - 10.
a(n) = A001020(n) + 1. (End)

A138530 Triangle read by rows: T(n,k) = sum of digits of n in base k representation, 1<=k<=n.

Original entry on oeis.org

1, 2, 1, 3, 2, 1, 4, 1, 2, 1, 5, 2, 3, 2, 1, 6, 2, 2, 3, 2, 1, 7, 3, 3, 4, 3, 2, 1, 8, 1, 4, 2, 4, 3, 2, 1, 9, 2, 1, 3, 5, 4, 3, 2, 1, 10, 2, 2, 4, 2, 5, 4, 3, 2, 1, 11, 3, 3, 5, 3, 6, 5, 4, 3, 2, 1, 12, 2, 2, 3, 4, 2, 6, 5, 4, 3, 2, 1, 13, 3, 3, 4, 5, 3, 7, 6, 5, 4, 3, 2, 1, 14, 3, 4, 5, 6, 4, 2, 7, 6, 5, 4, 3, 2, 1

Offset: 1

Reinhard Zumkeller, Mar 26 2008

A131383(n) = sum of n-th row;
A000027(n) = T(n,1);
A000120(n) = T(n,2) for n>1;
A053735(n) = T(n,3) for n>2;
A053737(n) = T(n,4) for n>3;
A053824(n) = T(n,5) for n>4;
A053827(n) = T(n,6) for n>5;
A053828(n) = T(n,7) for n>6;
A053829(n) = T(n,8) for n>7;
A053830(n) = T(n,9) for n>8;
A007953(n) = T(n,10) for n>9;
A053831(n) = T(n,11) for n>10;
A053832(n) = T(n,12) for n>11;
A053833(n) = T(n,13) for n>12;
A053834(n) = T(n,14) for n>13;
A053835(n) = T(n,15) for n>14;
A053836(n) = T(n,16) for n>15;
A007395(n) = T(n,n-1) for n>1;
A000012(n) = T(n,n).

			Start of the triangle for n in base k representation:
......................1
....................11....10
......... ........111....11...10
................1111...100...11..10
..............11111...101...12..11..10
............111111...110...20..12..11..10
..........1111111...111...21..13..12..11..10
........11111111..1000...22..20..13..12..11..10
......111111111..1001..100..21..14..13..12..11..10
....1111111111..1010..101..22..20..14..13..12..11..10
..11111111111..1011..102..23..21..15..14..13..12..11..10
111111111111..1100..110..30..22..20..15..14..13..12..11..10,
and the triangle of sums of digits starts:
......................1
.....................2...1
......... ..........3...2...1
...................4...1...2...1
..................5...2...3...2...1
.................6...2...2...3...2...1
................7...3...3...4...3...2...1
...............8...1...4...2...4...3...2...1
..............9...2...1...3...5...4...3...2...1
............10...2...2...4...2...5...4...3...2...1
...........11...3...3...5...3...6...5...4...3...2...1
..........12...2...2...3...4...2...6...5...4...3...2...1.

Alois P. Heinz, Rows n = 1..141, flattened
Eric Weisstein's World of Mathematics, Digit Sum

Cf. A007953. See A240236 for another version.

Cf. A002260.

a138530 n k = a138530_tabl !! (n-1) !! (k-1)
a138530_row n = a138530_tabl !! (n-1)
a138530_tabl = zipWith (map . flip q) [1..] a002260_tabl where
   q 1 n = n
   q b n = if n < b then n else q b n' + d where (n', d) = divMod n b
-- Reinhard Zumkeller, Apr 29 2015

T[n_, k_] := If[k == 1, n, Total[IntegerDigits[n, k]]];
Table[T[n, k], {n, 1, 14}, {k, 1, n}] // Flatten (* Jean-François Alcover, Oct 25 2021 *)

A176059 Periodic sequence: Repeat 3, 2.

Original entry on oeis.org

3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3

Offset: 0

Klaus Brockhaus, Apr 07 2010

Interleaving of A010701 and A007395.
Also continued fraction expansion of (3+sqrt(15))/2.
Also decimal expansion of 32/99.
a(n) = A010693(n+1).
Essentially first differences of A047218.
Binomial transform of 3 followed by -A122803.
Inverse binomial transform of 3 followed by A020714.
Second inverse binomial transform of A057198 without initial term 1.

Index entries for linear recurrences with constant coefficients, signature (0, 1).

Cf. A010701 (all 3's sequence), A007395 (all 2's sequence), A176058 (decimal expansion of (3+sqrt(15))/2), A010693 (repeat 2, 3), A047218 (congruent to {0, 3} mod 5), A122803 (powers of -2), A020714 (5*2^n), A057198 ((5*3^(n-1)+1)/2, n > 0).

Cf. A026532 (partial products).

a176059 = (3 -) . (`mod` 2) -- Reinhard Zumkeller, Nov 27 2012

a176059_list = cycle [3,2]  -- Reinhard Zumkeller, Apr 04 2012

&cat[ [3, 2]: n in [0..52] ];
[ (5+(-1)^n)/2: n in [0..104] ];

A176059:=n->(5+(-1)^n)/2; seq(A176059(n), n=0..100); # Wesley Ivan Hurt, Feb 26 2014

a[n_] := {3, 2}[[Mod[n, 2] + 1]]; Table[a[n], {n, 0, 104}] (* Jean-François Alcover, Jul 19 2013 *)
PadRight[{},120,{3,2}] (* Harvey P. Dale, Oct 06 2019 *)

a(n)=3-n%2 \\ Charles R Greathouse IV, Jul 13 2016

a(n) = (5+(-1)^n)/2.
a(n) = a(n-2) for n > 1; a(0) = 3, a(1) = 2.
a(n) = -a(n-1)+5 for n > 0; a(0) = 3.
a(n) = 3*((n+1) mod 2)+2*(n mod 2).
G.f.: (3+2*x)/((1-x)*(1+x)).
E.g.f.: 3*cosh(x) + 2*sinh(x). - Stefano Spezia, Aug 04 2025

A316828 Image of the Thue-Morse sequence A010060 under the morphism {1 -> 1,2; 0 -> 0,2}.

Original entry on oeis.org

0, 2, 1, 2, 1, 2, 0, 2, 1, 2, 0, 2, 0, 2, 1, 2, 1, 2, 0, 2, 0, 2, 1, 2, 0, 2, 1, 2, 1, 2, 0, 2, 1, 2, 0, 2, 0, 2, 1, 2, 0, 2, 1, 2, 1, 2, 0, 2, 0, 2, 1, 2, 1, 2, 0, 2, 1, 2, 0, 2, 0, 2, 1, 2, 1, 2, 0, 2, 0, 2, 1, 2, 0, 2, 1, 2, 1, 2, 0, 2, 0, 2, 1, 2, 1, 2, 0, 2, 1, 2, 0, 2, 0, 2, 1, 2, 0, 2, 1, 2, 1, 2, 0, 2, 1, 2

Offset: 0

N. J. A. Sloane, Jul 14 2018

nonn

The morphism is applied just once.
This is a word that is pure morphic and uniform primitive morphic, but neither pure uniform morphic nor pure primitive morphic.
A010060 interleaved with A007395. - Antti Karttunen, Oct 08 2018

Antti Karttunen, Table of n, a(n) for n = 0..65537
Jean-Paul Allouche, Julien Cassaigne, Jeffrey Shallit, and Luca Q. Zamboni, A Taxonomy of Morphic Sequences, arXiv:1711.10807 [cs.FL], 2017.

Cf. A010060.

Sequences mentioned in the Allouche et al. "Taxonomy" paper, listed by example number: 1: A003849, 2: A010060, 3: A010056, 4: A020985 and A020987, 5: A191818, 6: A316340 and A273129, 18: A316341, 19: A030302, 20: A063438, 21: A316342, 22: A316343, 23: A003849 minus its first term, 24: A316344, 25: A316345 and A316824, 26: A020985 and A020987, 27: A316825, 28: A159689, 29: A049320, 30: A003849, 31: A316826, 32: A316827, 33: A316828, 34: A316344, 35: A043529, 36: A316829, 37: A010060.

Riffle[ThueMorse[Range[0,100]],2] (* Paolo Xausa, Dec 18 2023 *)

A316828(n) = if(n%2,2,hammingweight(n/2)%2); \\ Antti Karttunen, Oct 08 2018

If n is odd, a(n) = 2, otherwise a(n) = A010060(n/2). - Antti Karttunen, Oct 08 2018

A144396 The odd numbers greater than 1.

Original entry on oeis.org

3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133

Offset: 1

Paul Curtz, Oct 03 2008

Last number of the n-th row of the triangle described in A142717.
If negated, these are also the values at local minima of the sequence A141620.
a(n) is the shortest leg of the n-th Pythagorean triple with consecutive longer leg and hypotenuse. The n-th such triple is given by (2n+1,2n^2+2n, 2n^2+2n+1), so that the longer legs are A046092(n) and the hypotenuses are A099776(n). - Ant King, Feb 10 2011
Numbers k such that the symmetric representation of sigma(k) has a pair of bars as its ends (cf. A237593). - Omar E. Pol, Sep 28 2018
Numbers k such that there is a prime knot with k crossings and braid index 2. (IS this true with "prime" removed?) - Charles R Greathouse IV, Feb 14 2023

Muniru A Asiru, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (2,-1)

Complement of A004275 and of A004277.
Cf. A000217, A002378, A005408, A007395, A046092, A099776, A237593, A254858.
Essentially the same as A140139, A130773, A062545, A020735, A005818.

List([3,5..200],n->n); # Muniru A Asiru, Sep 28 2018

a144396 = (+ 1) . (* 2)
a144396_list = [3, 5 ..] -- Reinhard Zumkeller, Feb 09 2015

seq(n,n=3..200,2); # Muniru A Asiru, Sep 28 2018

Range[3, 200, 2] (* Vladimir Joseph Stephan Orlovsky, Feb 19 2012 *)

a(n)=2*n+1 \\ Charles R Greathouse IV, Feb 14 2023

a(n) = A005408(n+1) = A000290(n+1) - A000290(n).
G.f.: x*(3-x)/(1-x)^2. - Jaume Oliver Lafont, Aug 30 2009
a(n) = A254858(n-1,2). - Reinhard Zumkeller, Feb 09 2015

Edited by R. J. Mathar, May 21 2009

A010722 Constant sequence: the all 6's sequence.

Original entry on oeis.org

6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6

Offset: 0

N. J. A. Sloane

Continued fraction expansion of 3+sqrt(10). - Bruno Berselli, Mar 15 2011
Decimal expansion of Sum_{n >= 0} n/binomial(2*n+1, n) = 2/3. - Bruno Berselli, Sep 14 2015
Decimal expansion of 2/3. - Franklin T. Adams-Watters, Feb 23 2019

John H. Conway and Richard K. Guy, The Book of Numbers, New York: Springer-Verlag, 1996. See p. 81.
David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987, p. 29.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1014.
Tanya Khovanova, Recursive Sequences.
Index to divisibility sequences.
Index entries for linear recurrences with constant coefficients, signature (1).

Cf. A145429: decimal expansion of Sum_{n >= 0} n/binomial(2*n, n).
Cf. A000012, A007395, A010701, A010709, A010716.
First differences of A008588.

a(n)=6 \\ Charles R Greathouse IV, Sep 28 2015

G.f.: 6/(1-x). - Bruno Berselli, Mar 15 2011
E.g.f.: 6*e^x. - Vincenzo Librandi, Jan 27 2012
a(n) = floor(1/(-n + csc(1/n))). - Clark Kimberling, Mar 10 2020

cp's OEIS Frontend

A010693 Periodic sequence: Repeat 2,3.

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A182406 Square array A(n,k), n>=1, k>=1, read by antidiagonals: A(n,k) is the number of n-colorings of the square grid graph G_(k,k).

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A000038 Twice A000007.

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Haskell

Mathematica

PARI

Formula

A010709 Constant sequence: the all 4's sequence.

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Maxima

PARI

Python

Formula

A034524 a(n) = 11^n + 1.

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Magma

Mathematica

PARI

Sage

Formula

A138530 Triangle read by rows: T(n,k) = sum of digits of n in base k representation, 1<=k<=n.

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Haskell

Mathematica

A176059 Periodic sequence: Repeat 3, 2.

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