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.

Previous Showing 11-15 of 15 results.

A070503 a(n) = n^3 mod 41.

Original entry on oeis.org

0, 1, 8, 27, 23, 2, 11, 15, 20, 32, 16, 19, 6, 24, 38, 13, 37, 34, 10, 12, 5, 36, 29, 31, 7, 4, 28, 3, 17, 35, 22, 25, 9, 21, 26, 30, 39, 18, 14, 33, 40, 0, 1, 8, 27, 23, 2, 11, 15, 20, 32, 16, 19, 6, 24, 38, 13, 37, 34, 10, 12, 5, 36, 29, 31, 7, 4, 28, 3, 17, 35, 22, 25, 9, 21, 26
Offset: 0

Views

Author

N. J. A. Sloane, May 12 2002

Keywords

Crossrefs

Cf. A008960.

Programs

Formula

a(n) = a(n-41). - G. C. Greubel, Mar 31 2016

A070597 Duplicate of A070474.

Original entry on oeis.org

0, 1, 8, 3, 4, 5, 0, 7, 8, 9, 4, 11, 0, 1, 8, 3, 4, 5, 0, 7, 8, 9, 4, 11, 0, 1, 8, 3, 4, 5, 0, 7, 8, 9, 4, 11, 0, 1, 8, 3, 4, 5, 0, 7, 8, 9, 4, 11, 0, 1, 8, 3, 4, 5, 0, 7, 8, 9, 4, 11, 0, 1, 8, 3, 4, 5, 0, 7, 8, 9, 4, 11, 0, 1, 8, 3, 4, 5, 0, 7, 8, 9, 4, 11, 0, 1, 8, 3, 4, 5, 0, 7, 8, 9, 4, 11, 0, 1, 8, 3
Offset: 0

Views

Author

N. J. A. Sloane, May 13 2002

Keywords

Comments

a(n)=A070474(n) [Proof: n^5-n^3 == 0 (mod 12) is shown explicitly for n=0 to 11, then the induction n->n+12 for the 5th-order polynomial followed by binomial expansion of (n+12)^k concludes that the zero (mod 12) is periodically extended to the other integers.] - R. J. Mathar, Jul 23 2009

Crossrefs

Programs

A282779 Period of cubes mod n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 3, 10, 11, 12, 13, 14, 15, 16, 17, 6, 19, 20, 21, 22, 23, 24, 25, 26, 9, 28, 29, 30, 31, 32, 33, 34, 35, 12, 37, 38, 39, 40, 41, 42, 43, 44, 15, 46, 47, 48, 49, 50, 51, 52, 53, 18, 55, 56, 57, 58, 59, 60, 61, 62, 21, 64, 65, 66, 67, 68, 69, 70, 71, 24, 73, 74, 75, 76, 77, 78, 79, 80, 27
Offset: 1

Views

Author

Ilya Gutkovskiy, Feb 21 2017

Keywords

Comments

The length of the period of A000035 (n=2), A010872 (n=3), A109718 (n=4), A070471 (n=5), A010875 (n=6), A070472 (n=7), A109753 (n=8), A167176 (n=9), A008960 (n = 10), etc. (see also comment in A000578 from R. J. Mathar).
Conjecture: let a_p(n) be the length of the period of the sequence k^p mod n where p is a prime, then a_p(n) = n/p if n == 0 (mod p^2) else a_p(n) = n.
For example: sequence k^7 mod 98 gives 1, 30, 31, 18, 19, 48, 49, 50, 79, 80, 67, 68, 97, 0, 1, 30, 31, 18, 19, 48, 49, 50, 79, 80, 67, 68, 97, 0, ... (period 14), 7 is a prime, 98 == 0 (mod 7^2) and 98/7 = 14.

Examples

			a(9) = 3 because reading 1, 8, 27, 64, 125, 216, 343, 512, ... modulo 9 gives 1, 8, 0, 1, 8, 0, 1, 8, 0, ... with period length 3.
		

Crossrefs

Programs

  • Mathematica
    a[1] = 1; a[n_] := For[k = 1, True, k++, If[Mod[k^3, n] == 0 && Mod[(k + 1)^3 , n] == 1, Return[k]]]; Table[a[n], {n, 1, 81}]

Formula

Apparently: a(n) = 2*a(n-9) - a(n-18).
Empirical g.f.: x*(1 + 2*x + 3*x^2 + 4*x^3 + 5*x^4 + 6*x^5 + 7*x^6 + 8*x^7 + 3*x^8 + 8*x^9 + 7*x^10 + 6*x^11 + 5*x^12 + 4*x^13 + 3*x^14 + 2*x^15 + x^16) / ((1 - x)^2*(1 + x + x^2)^2*(1 + x^3 + x^6)^2). - Colin Barker, Feb 21 2017

A070697 Duplicate of A070477.

Original entry on oeis.org

0, 1, 8, 12, 4, 5, 6, 13, 2, 9, 10, 11, 3, 7, 14, 0, 1, 8, 12, 4, 5, 6, 13, 2, 9, 10, 11, 3, 7, 14, 0, 1, 8, 12, 4, 5, 6, 13, 2, 9, 10, 11, 3, 7, 14, 0, 1, 8, 12, 4, 5, 6, 13, 2, 9, 10, 11, 3, 7, 14, 0, 1, 8, 12, 4, 5, 6, 13, 2, 9, 10, 11, 3, 7, 14, 0, 1, 8, 12, 4, 5, 6, 13, 2, 9, 10, 11, 3, 7, 14
Offset: 0

Views

Author

N. J. A. Sloane, May 13 2002

Keywords

Comments

a(n)=A070477(n). [Proof: (n^7-n^3) == 0 (mod 15) is shown for n=0 to 14 explicitly. Then binomial expansion of (n+15)^7 and (n+15)^3 extend this by induction n->n+15 to all other indices.] - R. J. Mathar, Oct 30 2009

Crossrefs

Cf. A008960.

Programs

A130875 Absolute difference of final digits of two consecutive cubes.

Original entry on oeis.org

1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1, 1, 3, 1, 7, 9, 1, 7, 1, 3, 1
Offset: 1

Views

Author

Giovanni Teofilatto, Jul 25 2007

Keywords

Comments

Periodic with period 10.

Crossrefs

Cf. A008960.

Programs

  • Mathematica
    LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 0, 1},{1, 7, 1, 3, 1, 1, 3, 1, 7, 9},105] (* Ray Chandler, Aug 26 2015 *)
    Abs[Differences[Mod[#,10]]]&/@Partition[Range[0,120]^3,2,1]//Flatten (* or *) PadRight[{},120,{1,7,1,3,1,1,3,1,7,9}] (* Harvey P. Dale, Oct 27 2019 *)
  • PARI
    Vec(-x*(9*x^9+7*x^8+x^7+3*x^6+x^5+x^4+3*x^3+x^2+7*x+1)/((x-1)*(x+1)*(x^4-x^3+x^2-x+1)*(x^4+x^3+x^2+x+1)) + O(x^100)) \\ Colin Barker, Dec 04 2014

Formula

a(n) = a(n-10). - Colin Barker, Dec 04 2014
G.f.: -x*(9*x^9+7*x^8+x^7+3*x^6+x^5+x^4+3*x^3+x^2+7*x+1) / ((x-1)*(x+1)*(x^4-x^3+x^2-x+1)*(x^4+x^3+x^2+x+1)). - Colin Barker, Dec 04 2014
Previous Showing 11-15 of 15 results.