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 1-10 of 13 results. Next

A180592 Digital root of 2n.

Original entry on oeis.org

0, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 6, 8, 1
Offset: 0

Views

Author

Odimar Fabeny, Sep 10 2010

Keywords

Comments

Period 9. - Robert G. Wilson v, Sep 20 2010
Also digital root of A002276(n). - Enrique Pérez Herrero, Nov 05 2022

Crossrefs

Programs

Formula

From R. J. Mathar, Nov 02 2010: (Start)
a(n) = A010888(2*n).
a(n) = a(n-9), n > 9.
G.f.: -x*(2 + 4*x + 6*x^2 + 8*x^3 + x^4 + 3*x^5 + 5*x^6 + 7*x^7 + 9*x^8) / ( (x-1)*(1 + x + x^2)*(x^6 + x^3 + 1) ). (End)

Extensions

More terms from Robert G. Wilson v, Sep 20 2010
Keyword:base and formulas from R. J. Mathar, Nov 02 2010

A180597 Digital root of 7n.

Original entry on oeis.org

0, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8, 6, 4, 2, 9, 7, 5, 3, 1, 8
Offset: 0

Views

Author

Odimar Fabeny, Sep 10 2010

Keywords

Comments

Period of 9. - Robert G. Wilson v, Sep 20 2010

Crossrefs

Programs

Formula

G.f.: x*(7 + 5*x + 3*x^2 + x^3 + 8*x^4 + 6*x^5 + 4*x^6 + 2*x^7 + 9*x^8)/(1 - x^9). - Stefano Spezia, Apr 21 2022
a(n) = A010888(A008589(n)). - Michel Marcus, Apr 21 2022

Extensions

More terms from Robert G. Wilson v, Sep 20 2010

A180598 Digital root of 8n.

Original entry on oeis.org

0, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4
Offset: 0

Views

Author

Odimar Fabeny, Sep 10 2010

Keywords

Comments

Period of 9. - Robert G. Wilson v, Sep 20 2010
Essentially the same as A138531. - R. J. Mathar, Jul 09 2011

Crossrefs

Programs

  • Mathematica
    f[n_] := Mod[8 n - 1, 9] + 1; f[0] = 0; Array[f, 105, 0] (* Robert G. Wilson v, Sep 20 2010 *)

Formula

G.f.: -x*(9*x^8+x^7+2*x^6+3*x^5+4*x^4+5*x^3+6*x^2+7*x+8)/((x-1)*(x^2+x+1)*(x^6+x^3+1)). - Colin Barker, Aug 19 2012
a(n) = A010888(8*n). - R. J. Mathar, Aug 28 2025

Extensions

More terms from Robert G. Wilson v, Sep 20 2010

A180593 Digital root of 3n.

Original entry on oeis.org

0, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6
Offset: 0

Views

Author

Odimar Fabeny, Sep 10 2010

Keywords

Comments

Decimal expansion of 41/1110. - Enrique Pérez Herrero, Nov 13 2021

Crossrefs

Cf. A008585 (3*n), A010888 (digital root), A002277.

Programs

  • Mathematica
    digitalRoot[n_Integer?Positive] := FixedPoint[Plus@@IntegerDigits[#]&,n]; Table[If[n==0,0,digitalRoot[3*n]], {n,0,200}] (* Vladimir Joseph Stephan Orlovsky, May 02 2011 *)
    LinearRecurrence[{0,0,1},{0,3,6,9},120] (* Harvey P. Dale, Sep 03 2020 *)

Formula

a(n+1) = 3*A010882(n). - Reinhard Zumkeller, Oct 25 2010
G.f.: (-3*(1 + 2*x + 3*x^2))/(-1 + x^3) for n>0. - Alexander R. Povolotsky, Jun 13 2012
a(n) = A010888(A002277(n)). - Enrique Pérez Herrero, Nov 24 2022
a(n) = A010888(A008585(n)). - Michel Marcus, Nov 24 2022

Extensions

Edited by N. J. A. Sloane, Sep 23 2010

A180594 Digital root of 4n.

Original entry on oeis.org

0, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2, 6, 1, 5, 9, 4, 8, 3, 7, 2
Offset: 0

Views

Author

Odimar Fabeny, Sep 10 2010

Keywords

Comments

Period of 9. - Robert G. Wilson v, Sep 20 2010

Crossrefs

Programs

  • Mathematica
    f[n_] := Mod[4 n - 1, 9] + 1; f[0] = 0; Array[f, 105, 0] (* Robert G. Wilson v, Sep 20 2010 *)
    Join[{0}, ReplaceAll[Table[Mod[4n, 9], {n, 99}], {0 -> 9}]] (* Alonso del Arte, Sep 23 2012 *)
    LinearRecurrence[{0,0,0,0,0,0,0,0,1},{0,4,8,3,7,2,6,1,5,9},120] (* or *) PadRight[ {0},120,{9,4,8,3,7,2,6,1,5}] (* Harvey P. Dale, Aug 09 2022 *)

Formula

G.f.: -x*(9*x^8+5*x^7+x^6+6*x^5+2*x^4+7*x^3+3*x^2+8*x+4)/((x-1)*(x^2+x+1)*(x^6+x^3+1)). - Colin Barker, Sep 23 2012

Extensions

More terms from Robert G. Wilson v, Sep 20 2010

A180595 Digital root of 5n.

Original entry on oeis.org

0, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7, 3, 8, 4, 9, 5, 1, 6, 2, 7
Offset: 0

Views

Author

Odimar Fabeny, Sep 10 2010

Keywords

Comments

Period of 9. - Robert G. Wilson v, Sep 20 2010

Crossrefs

Programs

  • Mathematica
    f[n_] := Mod[5 n - 1, 9] + 1; f[0] = 0; Array[f, 105, 0] (* Robert G. Wilson v, Sep 20 2010 *)
    Join[{0}, ReplaceAll[Table[Mod[5n, 9], {n, 99}], {0 -> 9}]] (* Alonso del Arte, Sep 23 2012 *)
    PadRight[{0},120,{9,5,1,6,2,7,3,8,4}] (* Harvey P. Dale, Jan 10 2024 *)

Formula

G.f.: -x*(9*x^8+4*x^7+8*x^6+3*x^5+7*x^4+2*x^3+6*x^2+x+5)/((x-1)*(x^2+x+1)*(x^6+x^3+1)). - Colin Barker, Sep 23 2012

Extensions

More terms from Robert G. Wilson v, Sep 20 2010

A180596 Digital root of 6n.

Original entry on oeis.org

0, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3, 9, 6, 3
Offset: 0

Views

Author

Odimar Fabeny, Sep 10 2010

Keywords

Comments

Period of 3. - Robert G. Wilson v, Sep 20 2010

Crossrefs

Programs

  • Mathematica
    f[n_] := Mod[6 n - 1, 9] + 1; f[0] = 0; Array[f, 105, 0] (* Robert G. Wilson v, Sep 20 2010 *)
    PadRight[{0},120,{9,6,3}] (* Harvey P. Dale, Dec 18 2012 *)

Formula

G.f.: 3*x*(2 + x + 3*x^2)/(1 - x^3). - Stefano Spezia, Apr 21 2022
a(n) = A010888(A008588(n)). - Michel Marcus, Apr 24 2022

Extensions

More terms from Robert G. Wilson v, Sep 20 2010

A353109 Array read by antidiagonals: A(n, k) is the digital root of n*k with n >= 0 and k >= 0.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 2, 2, 0, 0, 3, 4, 3, 0, 0, 4, 6, 6, 4, 0, 0, 5, 8, 9, 8, 5, 0, 0, 6, 1, 3, 3, 1, 6, 0, 0, 7, 3, 6, 7, 6, 3, 7, 0, 0, 8, 5, 9, 2, 2, 9, 5, 8, 0, 0, 9, 7, 3, 6, 7, 6, 3, 7, 9, 0, 0, 1, 9, 6, 1, 3, 3, 1, 6, 9, 1, 0, 0, 2, 2, 9, 5, 8, 9, 8, 5, 9, 2, 2, 0
Offset: 0

Views

Author

Stefano Spezia, Apr 24 2022

Keywords

Examples

			The array begins:
    0, 0, 0, 0, 0, 0, 0, 0, ...
    0, 1, 2, 3, 4, 5, 6, 7, ...
    0, 2, 4, 6, 8, 1, 3, 5, ...
    0, 3, 6, 9, 3, 6, 9, 3, ...
    0, 4, 8, 3, 7, 2, 6, 1, ...
    0, 5, 1, 6, 2, 7, 3, 8, ...
    0, 6, 3, 9, 6, 3, 9, 6, ...
    0, 7, 5, 3, 1, 8, 6, 4, ...
    ...
		

Crossrefs

Cf. A003991, A004247, A010888, A056992 (diagonal), A073636, A139413, A180592, A180593, A180594, A180595, A180596, A180597, A180598, A180599, A303296, A336225, A353128 (antidiagonal sums), A353933, A353974 (partial sum of the main diagonal).

Programs

  • Mathematica
    A[i_,j_]:=If[i*j==0,0,1+Mod[i*j-1,9]];Flatten[Table[A[n-k,k],{n,0,12},{k,0,n}]]
  • PARI
    T(n,k) = if (n && k, (n*k-1)%9+1, 0); \\ Michel Marcus, May 12 2022

Formula

A(n, k) = A010888(A004247(n, k)).
A(n, k) = A010888(A003991(n, k)) for n*k > 0.

A139413 Triangle read by rows: row n gives the numbers A010888(n*k) for k = 1..n.

Original entry on oeis.org

1, 2, 4, 3, 6, 9, 4, 8, 3, 7, 5, 1, 6, 2, 7, 6, 3, 9, 6, 3, 9, 7, 5, 3, 1, 8, 6, 4, 8, 7, 6, 5, 4, 3, 2, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 4, 6, 8, 1, 3, 5, 7, 9, 2, 4, 3, 6, 9, 3, 6, 9, 3, 6, 9, 3, 6, 9, 4
Offset: 1

Views

Author

Philippe Lallouet (philip.lallouet(AT)orange.fr), Apr 19 2008

Keywords

Examples

			Triangle begins:
1
2 4
3 6 9
4 8 3 7
5 1 6 2 7
6 3 9 6 3 9
7 5 3 1 8 6 4
8 7 6 5 4 3 2 1
9 9 9 9 9 9 9 9 9
...
		

Crossrefs

Cf. A007953 (column 1), A180592 - A180599 (columns 2 - 9), A010888, A038194.

Programs

  • Maple
    A010888:=proc(n) return ((n-1) mod 9)+1; end:
    for n from 1 to 9 do for k from 1 to n do printf("%d ",A010888(n*k)); od: printf("\n"): od: # Nathaniel Johnston, Apr 21 2011
  • Mathematica
    Table[FixedPoint[Total@ IntegerDigits[#] &, n k], {n, 13}, {k, n}] // Flatten (* Michael De Vlieger, Oct 31 2021 *)

Extensions

More terms and several terms corrected by Nathaniel Johnston, Apr 21 2011

A337127 Table with 10 columns read by rows: T(n, k) is the number of n-digit positive integers with exactly k distinct base 10 digits (0 < k <= 10).

Original entry on oeis.org

9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 81, 0, 0, 0, 0, 0, 0, 0, 0, 9, 243, 648, 0, 0, 0, 0, 0, 0, 0, 9, 567, 3888, 4536, 0, 0, 0, 0, 0, 0, 9, 1215, 16200, 45360, 27216, 0, 0, 0, 0, 0, 9, 2511, 58320, 294840, 408240, 136080, 0, 0, 0, 0, 9, 5103, 195048, 1587600, 3810240, 2857680, 544320, 0, 0, 0
Offset: 1

Views

Author

Stefano Spezia, Aug 17 2020

Keywords

Examples

			The table T(n, k) begins:
9     0      0       0       0       0  0  0  0  0
9    81      0       0       0       0  0  0  0  0
9   243    648       0       0       0  0  0  0  0
9   567   3888    4536       0       0  0  0  0  0
9  1215  16200   45360   27216       0  0  0  0  0
9  2511  58320  294840  408240  136080  0  0  0  0
...
		

Crossrefs

Cf. A010734, A048993, A052268 (row sums), A073531 (diagonal), A180599 (k = 1), A335843 (k = 2), A337313 (k = 3).

Programs

  • Mathematica
    T[n_,k_]:=9Pochhammer[11-k,k-1]/k!*n!*Coefficient[Series[(Exp[x]-1)^k,{x,0,n}],x,n]; Table[T[n,k],{n,7},{k,10}]//Flatten

Formula

T(n, k) = 9*Pochhammer(11-k, k-1)*n! * [x^n] (exp(x) - 1)^k/k!.
T(n, k) = 9*Pochhammer(11-k, k-1) * [x^n] x^k/Product_{j=1..k} (1-j*x).
T(n, k) = 9*Pochhammer(11-k, k-1)*S2(n, k) where S2(n, k) = A048993(n, k) are the Stirling numbers of the 2nd kind.
Showing 1-10 of 13 results. Next