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 1-9 of 9 results.

A061672 Smallest positive number formed by a set of digits whose product = sum of the digits.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 22, 123, 1124, 11125, 11133, 11222, 111126, 1111127, 1111134, 11111128, 11111223, 111111129, 111111135, 1111111144, 11111111136, 11111111224, 111111112222, 1111111111137, 1111111111145, 1111111111233
Offset: 1

Views

Author

Amarnath Murthy, Jun 26 2001

Keywords

Comments

From M. F. Hasler, Oct 29 2014: (Start)
This is the subsequence of terms of A034710 with digits in nondecreasing order, which is meant by "smallest": For example, 132 also has sum of digits = product of digits, but is already "represented" by 123. The word "set" in the definition actually means "multiset".
The sequence is infinite: for any number N whose digits form a nondecreasing sequence whose sum of digits S is not larger than the product of digits P (i.e., N in A062998), a term of the sequence is obtained by prefixing N with P-S digits '1'. (End)

Examples

			1124 is a term since 1 + 1 + 2 + 4 = 1*1*2*4 = 8.
		

Crossrefs

Programs

  • PARI
    is_A061672(n)={vecsort(n=digits(n))==n && normlp(n,1)==prod(i=1,#n,n[i])} \\ M. F. Hasler, Oct 29 2014

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jun 27 2001
Corrected by Franklin T. Adams-Watters, Oct 25 2006
Further corrections from T. D. Noe, Oct 12 2007

A062996 Numbers whose sum of digits is greater than or equal to its product of digits.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 30, 31, 40, 41, 50, 51, 60, 61, 70, 71, 80, 81, 90, 91, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 130, 131, 132
Offset: 1

Views

Author

Henry Bottomley, Jun 29 2001

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[150],Total[IntegerDigits[#]]>=Times@@IntegerDigits[#]&] (* Harvey P. Dale, Sep 27 2023 *)
  • PARI
    isok(k)={my(d=digits(k)); vecsum(d) >= vecprod(d)} \\ Harry J. Smith, Aug 15 2009

A062329 a(n) = (sum of digits of n) - (product of digits of n).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 0, -1, -2, -3, -4, -5, -6, -7, 3, 1, -1, -3, -5, -7, -9, -11, -13, -15, 4, 1, -2, -5, -8, -11, -14, -17, -20, -23, 5, 1, -3, -7, -11, -15, -19, -23, -27, -31, 6, 1, -4, -9, -14, -19, -24, -29, -34, -39, 7, 1, -5, -11, -17, -23, -29, -35, -41, -47, 8, 1, -6, -13, -20, -27
Offset: 0

Views

Author

Amarnath Murthy, Jun 21 2001

Keywords

Examples

			a(23) = 2 + 3 - 2*3 = -1.
a(49) = -(4*9) + (4 + 9) = -36 + 13 = -23.
		

Crossrefs

Programs

  • Mathematica
    a[n_] := (t = IntegerDigits[n]; Plus @@ t - Times @@ t); Table[ a[n], {n, 0, 75}] (* Robert G. Wilson v *)

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jun 22 2001
Signed version from Henry Bottomley, Jun 29 2001

A062997 Numbers whose sum of digits is strictly greater than its product of digits.

Original entry on oeis.org

10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 30, 31, 40, 41, 50, 51, 60, 61, 70, 71, 80, 81, 90, 91, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 130, 131, 140, 141, 150, 151, 160, 161, 170
Offset: 1

Views

Author

Amarnath Murthy, Jun 27 2001

Keywords

Comments

Every multiple of 10 is a term.

Examples

			118 is a term as 1 + 1 + 8 = 10, 10 > 8 and 8 = 1 * 1 * 8.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[170], (Plus @@ IntegerDigits[ # ]) > (Times @@ IntegerDigits[ # ]) &] (* Alonso del Arte, May 16 2005 *)
  • PARI
    isok(k)={my(d=digits(k)); vecsum(d) > vecprod(d)} \\ Harry J. Smith, Aug 15 2009

Extensions

Extended by Larry Reeves (larryr(AT)acm.org) and Henry Bottomley, Jun 29 2001

A062999 Numbers whose sum of the digits is strictly less than its product of digits.

Original entry on oeis.org

23, 24, 25, 26, 27, 28, 29, 32, 33, 34, 35, 36, 37, 38, 39, 42, 43, 44, 45, 46, 47, 48, 49, 52, 53, 54, 55, 56, 57, 58, 59, 62, 63, 64, 65, 66, 67, 68, 69, 72, 73, 74, 75, 76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 88, 89, 92, 93, 94, 95, 96, 97, 98, 99, 124, 125, 126, 127
Offset: 1

Views

Author

Henry Bottomley, Jun 29 2001

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[128], (Plus @@ IntegerDigits[ # ]) < (Times @@ IntegerDigits[ # ]) &] (* Alonso del Arte, May 16 2005 *)
  • PARI
    isok(k)={my(d=digits(k)); vecsum(d) < vecprod(d)} \\ Harry J. Smith, Aug 15 2009

A037344 Numbers whose base-2 and base-10 expansions have no digits in common.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 8, 9, 22, 23, 24, 25, 26, 27, 28, 29, 32, 33, 34, 35, 36, 37, 38, 39, 42, 43, 44, 45, 46, 47, 48, 49, 52, 53, 54, 55, 56, 57, 58, 59, 62, 63, 64, 65, 66, 67, 68, 69, 72, 73, 74, 75, 76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 88, 89, 92, 93, 94, 95, 96, 97, 98, 99, 222
Offset: 1

Views

Author

Keywords

Crossrefs

Not the same as A062998 or A387032.

Programs

  • Maple
    isA037344 := proc(n)
        local dgs10,dgs2 ;
        dgs10 := convert(convert(n,base,10),set) ;
        dgs2 := convert(convert(n,base,2),set) ;
        if dgs10 intersect dgs2 = {} then
            true ;
        else
            false ;
        end if;
    end proc:
    A037344 := proc(n)
        option remember ;
        local a;
        if n = 1 then
            2;
        else
            for a from procname(n-1)+1 do
                if isA037344(a) then
                    return a;
                end if;
            end do;
        end if;
    end proc:
    seq(A037344(n),n=1..200) ; # R. J. Mathar, Aug 14 2025
  • Mathematica
    Select[Range[100],Intersection[IntegerDigits[#,2],IntegerDigits[#,10]]=={}&] (* Vincenzo Librandi, Jun 06 2012 *)

A254621 Zerofree numbers having product of digits less than or equal to sum of digits.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 31, 41, 51, 61, 71, 81, 91, 111, 112, 113, 114, 115, 116, 117, 118, 119, 121, 122, 123, 131, 132, 141, 151, 161, 171, 181, 191, 211, 212, 213, 221, 231, 311, 312, 321, 411
Offset: 1

Views

Author

David A. Corneth, Feb 03 2015

Keywords

Comments

Intersection of A052382 and A062996.
The repunit A002275(k), for k >= 2, appears at position A254622(k-1) + 1. - Wolfdieter Lang, Feb 23 2015

Crossrefs

Programs

  • Maple
    extend:= proc(t, b, d)
      local i,j,m,s,p;
      p:= t[2];
      s:= t[3];
      if s = 0  then if b=2 then j:= 3 else j:= 2 fi
      else  for j from 0 to d-nops(t[1]) while p*b^j <= s + j*b do od
      fi:
      seq([[op(t[1]),b$i],p*b^i,s+i*b],i=0..j-1);
    end proc:
    f:= proc(d)
       local j, b, Res;
       Res:= [seq([[1$j],1,j],j=0..d)];
       for b from 2 to 9 do
         Res:= map(extend,Res,b,d)
       od:
       Res:= map(t -> op(combinat:-permute(t[1])),Res);
       subs(0=NULL,sort(map(t -> add(t[i]*10^(i-1),i=1..nops(t)), Res)));
    end proc:
    f(5); # Robert Israel, May 19 2015
  • Mathematica
    m[w_] := Flatten@Table[i, {i,9}, {w[[i]]}]; a[upd_] := Union@ Flatten@ Table[ FromDigits /@ Flatten[Permutations /@ m /@ Select[ Flatten[ Permutations /@ (IntegerPartitions[d + 9, {9}, Range[d + 1]] - 1), 1], Times @@ (Range[9]^#) <= Total[# Range[9]] &], 1], {d,  upd}]; a[12] (* terms with up to 12 digits, Giovanni Resta, May 19 2015 *)
    zfnQ[n_]:=Module[{idn=IntegerDigits[n]},FreeQ[idn,0]&&Times@@idn <= Total[ idn]]; Select[Range[500],zfnQ] (* Harvey P. Dale, Jun 29 2019 *)
  • PARI
    is(n)={my(d=digits(n));my(p=prod(i=1,#d,d[i])); 0 < p && p<=vecsum(d) } \\ David A. Corneth, May 15 2015

A387032 Numbers k with digits different from 0 and 1.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 8, 9, 22, 23, 24, 25, 26, 27, 28, 29, 32, 33, 34, 35, 36, 37, 38, 39, 42, 43, 44, 45, 46, 47, 48, 49, 52, 53, 54, 55, 56, 57, 58, 59, 62, 63, 64, 65, 66, 67, 68, 69, 72, 73, 74, 75, 76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 88, 89, 92, 93, 94, 95, 96, 97, 98, 99, 222
Offset: 1

Views

Author

David A. Corneth, Aug 13 2025

Keywords

Comments

A062998 contains numbers like 123, 124, 125,.. which are not in this sequence. - R. J. Mathar, Aug 14 2025
A037344 contains numbers like 2047 and 4095 which are not in this sequence. - R. J. Mathar, Aug 14 2025

Examples

			2 is in the sequence since it does not contain 0 nor 1.
12 is not in the sequence since it has digit 1.
		

Crossrefs

Intersection of A052382 and A052383.

Programs

  • Maple
    isA387032 := proc(n)
        local d ;
        for d in convert(n,base,10) do
            if d <=1 then
                return false;
            end if;
        end do:
        true ;
    end proc:
    A387032 := proc(n)
        option remember ;
        local a;
        if n = 1 then
            2;
        else
            for a from procname(n-1)+1 do
                if isA387032(a) then
                    return a;
                end if;
            end do;
        end if;
    end proc:
    seq(A387032(n),n=1..200) ; # R. J. Mathar, Aug 14 2025
  • Mathematica
    Select[Range[222], Total@ DigitCount[#, 10, {0, 1}] == 0 &] (* Michael De Vlieger, Aug 13 2025 *)
  • PARI
    is(n) = if(n <= 0, return(0)); Set(digits(n))[1] >= 2
    
  • Python
    def ok(n): return {"0","1"} & set(str(n)) == set()
    print([k for k in range(223) if ok(k)]) # Michael S. Branicky, Aug 13 2025
    
  • Python
    def A387032(n):
        m = ((k:=7*n+1).bit_length()-1)//3
        return sum((2+((k-(1<<3*m))//(7<<3*j)&7))*10**j for j in range(m)) # Chai Wah Wu, Aug 13 2025

A249443 Numbers with digits in nondecreasing order and digital sum not larger than the product of the digits.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 22, 23, 24, 25, 26, 27, 28, 29, 33, 34, 35, 36, 37, 38, 39, 44, 45, 46, 47, 48, 49, 55, 56, 57, 58, 59, 66, 67, 68, 69, 77, 78, 79, 88, 89, 99, 123, 124, 125, 126, 127, 128, 129, 133, 134, 135, 136, 137, 138, 139, 144, 145, 146, 147, 148, 149, 155, 156, 157, 158
Offset: 1

Views

Author

M. F. Hasler, Oct 29 2014

Keywords

Comments

Intersection of A009994 and A062998.
Except for the initial 0, a subsequence of the zeroless numbers A052382.
The nonzero terms of this sequence correspond to a term of A061672 obtained by concatenation with A002275(A007954(a(n))-A007953(a(n))).

Crossrefs

Programs

  • PARI
    is(n)={vecsort(n=digits(n))==n && normlp(n,1)<=prod(i=1,#n,n[i])}
Showing 1-9 of 9 results.