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 1-4 of 4 results.

A045876 Sum of different permutations of digits of n (leading 0's allowed).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 11, 33, 44, 55, 66, 77, 88, 99, 110, 22, 33, 22, 55, 66, 77, 88, 99, 110, 121, 33, 44, 55, 33, 77, 88, 99, 110, 121, 132, 44, 55, 66, 77, 44, 99, 110, 121, 132, 143, 55, 66, 77, 88, 99, 55, 121, 132, 143, 154, 66, 77, 88, 99, 110, 121, 66, 143
Offset: 1

Views

Author

Keywords

Comments

Let the arithmetic mean of the digits of a 'D' digit number n be 'A', let 'N' = number of distinct numbers that can be formed by permuting the digits of n, and let 'I' = concatenation of 1 'D' times = (10^D-1)/9. then a(n) = A*N*I. E.g., let n = 324541, then A = (3+2+4+5+4+1)/6 = 19/6, N = 6!/(2!) = 360, I = 111111, and a(n) = A*N*I = (19/6)*(360)*(111111) = 126666540. - Amarnath Murthy, Jul 14 2003
It seems that the first person who studied the sum of different permutations of digits of a given number was the French scientist Eugène Aristide Marre (1823-1918). See links. - Bernard Schott, Dec 06 2012

References

  • Amarnath Murthy, An interesting result in combinatorics, Mathematics & Informatics Quarterly, Vol. 3, 1999, Bulgaria.

Crossrefs

Same beginning as A033865. Cf. A061147.

Programs

  • Maple
    f:= proc(x) local L,D,n,M,s,j;
      L:= convert(x,base,10);
      D:= [seq(numboccur(j,L),j=0..9)];
      n:= nops(L);
      M:= n!/mul(d!,d=D);
      s:= add(j*D[j+1],j=0..9);
      (10^n-1)*M/9/n*s
    end proc:
    map(f, [$1..100]); # Robert Israel, Jul 07 2015
  • Mathematica
    Table[Total[FromDigits /@ Permutations[IntegerDigits[n]]], {n, 100}] (* T. D. Noe, Dec 06 2012 *)
  • PARI
    A047726(n) = n=eval(Vec(Str(n))); (#n)!/prod(i=0, 9, sum(j=1, #n, n[j]==i)!);
    A055642(n) = #Str(n);
    A007953(n) = sumdigits(n);
    a(n) = ((10^A055642(n)-1)/9)*(A047726(n)*A007953(n)/A055642(n)); \\ Altug Alkan, Aug 29 2016
    
  • PARI
    A045876(n) = {my(d=digits(n), q=1, v, t=1); v = vecsort(d); for(i=1, #v-1, if(v[i]==v[i+1], t++, q*=binomial(i, t); t=1)); q*binomial(#v, t)*(10^#d-1)*vecsum(d)/9/#d} \\ David A. Corneth, Oct 06 2016

Formula

a(n) = ((10^A055642(n)-1)/9)*(A047726(n)*A007953(n)/A055642(n)). - Altug Alkan, Aug 29 2016

A061378 Product of all numbers formed by permuting the digits of n.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 121, 252, 403, 574, 765, 976, 1207, 1458, 1729, 40, 252, 484, 736, 1008, 1300, 1612, 1944, 2296, 2668, 90, 403, 736, 1089, 1462, 1855, 2268, 2701, 3154, 3627, 160, 574, 1008, 1462, 1936, 2430, 2944, 3478, 4032, 4606, 250
Offset: 0

Views

Author

Klaus Brockhaus, Jun 08 2001

Keywords

Comments

Differs from A062003 at those n which have more than two digits.

Examples

			a(10) = 10*01 = 10, a(11) = 11*11 = 121, a(12) = 12*21 =252.
		

Crossrefs

Programs

  • ARIBAS
    : function permute(s: string): array; var i,k: integer; st1,st2: stack; ele,ws: string; begin stack_push(st2,s[0..0]); for i := 1 to length(s)-1 do while not stack_empty(st2) do stack_push(st1,stack_pop(st2)); end; ele := s[i]; while length(st1) > 0 do ws := stack_pop(st1); for k := 0 to length(ws)-1 do stack_push(st2,concat(ws[0..k-1],ele,ws[k..])); end; stack_push(st2,concat(ws[0..],ele)); end; end; return stack2array(st2); end; function int_permute(n: integer): array; var s: string; ar: array; i: integer; begin s := itoa(n); ar := permute(s); for i := 0 to length(ar)-1 do ar[i] := atoi(ar[i]); end; return ar; end; for k := 0 to 55 do write(product(int_permute(k))," "); end;

A062003 Product of the k numbers formed by cyclically permuting digits of n (where k = number of digits of n).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 252, 403, 574, 765, 976, 1207, 1458, 1729, 40, 252, 22, 736, 1008, 1300, 1612, 1944, 2296, 2668, 90, 403, 736, 33, 1462, 1855, 2268, 2701, 3154, 3627, 160, 574, 1008, 1462, 44, 2430, 2944, 3478, 4032, 4606, 250
Offset: 0

Views

Author

Amarnath Murthy, May 30 2001

Keywords

Comments

Apparently some kind of distinctness is required, because n=11 (cyclically permuted again 11) is not translated to 11*11=121. - R. J. Mathar, Jun 13 2025

Examples

			a(14) = 14*41 = 574, a(100) = 100*010*001 = 1000, a(102) = 102*210*21 = 449820.
		

Crossrefs

Programs

  • ARIBAS
    for k := 0 to 60 do st := itoa(k); m := 1; for i := 1 to length(st) do st := concat(st[1..length(st)-1],st[0]); m := m*atoi(st); end; write(m," "); end;

Extensions

Corrected and extended by Frank Ellermann and Klaus Brockhaus, Jun 03 2001

A179055 Numbers k such that the product of all numbers formed by cyclically permuting digits of k is a square.

Original entry on oeis.org

1, 4, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 243, 324, 432, 567, 675, 756, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1111, 1212, 1313, 1414, 1515, 1616, 1717, 1818, 1919, 2000, 2010, 2020, 2030, 2040, 2050, 2060, 2070, 2080, 2090, 2121, 2222, 2323, 2424
Offset: 1

Views

Author

Michel Lagneau, Jan 04 2011

Keywords

Examples

			756 is in the sequence because 756 * 567 * 675 = 289340100 = 17010^2.
		

Crossrefs

Programs

  • Maple
    with(numtheory):for n from 1 to 4000 do:pp:=1:n0:=n:l:=length(n0) :ind:=0:for
      j from 1 to l do:s:=0:for m from 1 to l do:q:=n0:u:=irem(q, 10):v:=iquo(q, 10):n0:=v
      :s:=s+ u*10^m:od:s:=floor(s-u*10^l+u):n0:=s: pp:=pp*s:od:x:=sqrt(pp) :y:=floor(x):if
      x=y then printf(`%d, `, n): else fi :od:
  • Mathematica
    cycDigitPerms[n_Integer, b_:10] := Module[{list = {n}, digits = IntegerDigits[n, b], len, counter, holder, next}, len = Length[digits]; counter = 1; While[counter < len, holder = digits[[-1]]; digits = Drop[digits, -1]; digits = Insert[digits, holder, 1]; list = Append[list, FromDigits[digits, b]]; counter++]; Return[list]]; Select[Range[2000], IntegerQ[Sqrt[Times@@cycDigitPerms[#]]] &] (* Alonso del Arte, Jan 04 2011 *)
Showing 1-4 of 4 results.