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.

A119626 Erroneous version of A178674.

Original entry on oeis.org

6, 12, 30, 84, 246, 732, 2790, 8364, 25086, 75252, 225750, 677264
Offset: 1

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Author

Keywords

A168609 a(n) = 3^n + 4.

Original entry on oeis.org

5, 7, 13, 31, 85, 247, 733, 2191, 6565, 19687, 59053, 177151, 531445, 1594327, 4782973, 14348911, 43046725, 129140167, 387420493, 1162261471, 3486784405, 10460353207, 31381059613, 94143178831, 282429536485, 847288609447
Offset: 0

Views

Author

Vincenzo Librandi, Dec 01 2009

Keywords

Examples

			a(1)=3*5-8=7; a(2)=3*7-8=13; a(3)=3*13-8=31.
		

Crossrefs

Programs

Formula

a(n) = 3*a(n-1) - 8, with n>0, a(0)=5.
G.f.: (5 - 13*x)/((1-x)*(1-3 x)). - Vincenzo Librandi, May 13 2014
a(n) = 4*a(n-1) - 3*a(n-2) for n>1. - Vincenzo Librandi, May 13 2014
E.g.f.: exp(3*x) + 4*exp(x). - G. C. Greubel, Jul 27 2016

Extensions

Formula and examples edited to use correct offset by Jon E. Schoenfield, Jun 19 2010

A178675 a(n) = 4^n + 4.

Original entry on oeis.org

5, 8, 20, 68, 260, 1028, 4100, 16388, 65540, 262148, 1048580, 4194308, 16777220, 67108868, 268435460, 1073741828, 4294967300, 17179869188, 68719476740, 274877906948, 1099511627780, 4398046511108, 17592186044420, 70368744177668, 281474976710660, 1125899906842628
Offset: 0

Views

Author

Vincenzo Librandi, Dec 25 2010

Keywords

Crossrefs

Programs

  • GAP
    List([0..30], n -> 4^n + 4); # G. C. Greubel, Jan 27 2019
  • Magma
    [4^n+4: n in [0..35]];
    
  • Magma
    I:=[5, 8]; [n le 2 select I[n] else 5*Self(n-1)-4*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Jun 18 2013
    
  • Mathematica
    Table[4^n +4, {n, 0, 40}] (* or *) CoefficientList[Series[(5-17x)/((4x - 1)(x-1)), {x, 0, 30}], x] (* Vincenzo Librandi, Jun 18 2013 *)
    LinearRecurrence[{5,-4},{5,8},30] (* Harvey P. Dale, Sep 12 2023 *)
  • PARI
    vector(40, n, n--; 4^n+4) \\ G. C. Greubel, Jan 27 2019
    
  • Sage
    [4^n+4 for n in range(40)] # G. C. Greubel, Jan 27 2019
    

Formula

a(n) = 4*(a(n-1) - 3) with n > 0, a(0)=5.
G.f.: ( 5-17*x ) / ( (1-4*x)*(1-x) ). - R. J. Mathar, Jan 05 2011
a(n) = 5*a(n-1) - 4*a(n-2). - Vincenzo Librandi, Jun 18 2013
E.g.f.: exp(4*x) + 4*exp(x). - G. C. Greubel, Jan 27 2019

A301919 a(n) is the least value of k for which A301918(n) divides 3^k+3.

Original entry on oeis.org

0, 1, 3, 4, 9, 10, 15, 16, 10, 5, 22, 27, 6, 12, 7, 40, 45, 25, 51, 18, 57, 64, 69, 70, 75, 26, 40, 82, 87, 9, 99, 100, 106, 112, 117, 61, 129, 135, 16, 141, 142, 147, 18, 159, 166, 85, 88, 177, 62, 94, 190, 195, 100, 201, 103, 74, 225, 115, 231, 232, 244, 84
Offset: 1

Views

Author

Luke W. Richards, Mar 28 2018

Keywords

Comments

This can be used to identify P+1 values to primality test potential primes P of the form 3^k+2, i.e., A051783.

Examples

			All values of 3^k+3 are multiples of 2, so 3^0+3 = 4 is the least value of k which is a multiple of 2.
a(10) = 5 and A301918(10) = 41 so 3^5+3 = 246 is the first multiple of 41 which can be written in the form 3^k+3.
		

Crossrefs

Formula

a(n) = A301917(n-1) + 1 for n > 2.

A161720 a(n) = (prime(n) - 7)/2.

Original entry on oeis.org

-1, 0, 2, 3, 5, 6, 8, 11, 12, 15, 17, 18, 20, 23, 26, 27, 30, 32, 33, 36, 38, 41, 45, 47, 48, 50, 51, 53, 60, 62, 65, 66, 71, 72, 75, 78, 80, 83, 86, 87, 92, 93, 95, 96, 102, 108, 110, 111, 113, 116, 117, 122, 125, 128, 131, 132
Offset: 3

Views

Author

G. A. Isa (isaabor(AT)yahoo.com), Jun 18 2009

Keywords

Comments

Original name was: Half the difference between the first and the last numbers in the 7th circle of the cyclic representation of some structures whose cardinality generates Aminu numbers.
A bijective operator is defined on the Aminu numbers which in turn generates another cyclic group. Aminu numbers were first reported as the cardinality of some subgroups of regular groups whose order and degree coincide (Ibrahim,2004;2005;2007 and Ibrahim and Audu 2005). The action of the operator on the group structures where constructed using some special succession scheme which led to sequences such as A005097. This sequence enumerates half the difference between the first and last numbers in the 7th cycle of such group structures.

Examples

			For Pn=5, a(1)=-2/2=-1, for Pn=7, a(2)=0/2=0, for Pn=11,a(3)=4/2=2
		

References

  • A. A. Ibrahim, Group theoretic interpretation of Bara'a al-Dhimmah Models: Proceedings of Annual National Conference of Mathematical Association of Nigeria, MAN,(2004), 35-40.
  • A. A. Ibrahim and M. S. Audu, Some Group Theoretic Properties of Certain class of (123) and (132)- Avoiding Patterns of numbers: An enumeration scheme,African Journal of Natural Sciences, 8(1)(2005), 79-84.
  • A. A. Ibrahim, An Enumeration scheme and Algebraic properties of a special (132)- avoiding class of permutations Patterns, Trends in Applied sciences Research, Academic Journal Inc. 2(4)(2007), 334-340.

Crossrefs

Essentially a duplicate of A105760.

Programs

Formula

a(n) = A105760(n-3). - R. J. Mathar, Sep 11 2012

Extensions

Name changed by Arkadiusz Wesolowski, Jun 15 2013
Showing 1-5 of 5 results.