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 23 results. Next

A096287 Number of iterations of n -> n + (product of nonzero digits of n) needed for the trajectory of n to join the trajectory of A063108.

Original entry on oeis.org

0, 0, 5, 0, 6, 4, 3, 0, 2, 5, 4, 3, 1, 2, 2, 0, 3, 1, 5, 1, 10, 0, 9, 2, 7, 0, 9, 4, 8, 8, 5, 1, 7, 4, 6, 2, 15, 0, 2, 4, 8, 6, 5, 3, 7, 3, 7, 4, 16, 5, 17, 1, 2, 1, 4, 16, 7, 14, 1, 2, 4, 0, 322, 3, 6, 1, 3, 1, 17, 2, 16, 16, 17, 0, 6, 2, 1, 15, 14, 3, 321, 14, 4, 1, 15, 15, 13, 2, 320, 12, 3, 6, 2, 16
Offset: 1

Views

Author

Jason Earls, Jun 23 2004

Keywords

Comments

Loomis has verified that all n up to 1000000 eventually join the trajectory of A063108.

Examples

			a(3)=5 because the trajectory for 1 (Sequence A063108) starts
1->2->4->8->16->22->26->38->62->74...
and the sequence for 3 starts
3->6->12->14->18->26->38->62->74...
so the sequence beginning with 3 joins A063108 after 5 steps.
		

Programs

  • C
    See Link section.

A063114 a(n) = n + product of the nonzero digits of n.

Original entry on oeis.org

2, 4, 6, 8, 10, 12, 14, 16, 18, 11, 12, 14, 16, 18, 20, 22, 24, 26, 28, 22, 23, 26, 29, 32, 35, 38, 41, 44, 47, 33, 34, 38, 42, 46, 50, 54, 58, 62, 66, 44, 45, 50, 55, 60, 65, 70, 75, 80, 85, 55, 56, 62, 68, 74, 80, 86, 92, 98, 104, 66, 67, 74, 81, 88, 95, 102, 109, 116
Offset: 1

Views

Author

N. J. A. Sloane, Aug 08 2001

Keywords

Examples

			a(59) = 59 + 5*9 = 104. a(66) = 66 + 6*6 = 102.
		

Crossrefs

Programs

  • ARIBAS
    var stk: stack; end; for n := 1 to 80 do s := itoa(n); for j := 0 to length(s) -1 do k := atoi(s[j..j]); if k > 0 then stack_push(stk,k); end; end; write(n + product(stack2array(stk))," "); end;
    
  • Haskell
    a063114 n = n + a051801 n -- Reinhard Zumkeller, Jan 15 2012
  • Mathematica
    Table[i+Times@@(IntegerDigits[i]/. 0->1), {i, 70}]
  • PARI
    a(n) = n + vecprod(select(x->(x!=0), digits(n))) \\ Harry J. Smith, Aug 19 2009
    

Formula

a(n) = n + A051801(n). - Reinhard Zumkeller, Jan 15 2012

Extensions

More terms from Robert G. Wilson v and Klaus Brockhaus, Aug 09 2001

A096922 Numbers n for which there is a unique k such that n = k + (product of nonzero digits of k).

Original entry on oeis.org

2, 4, 6, 8, 10, 11, 20, 23, 24, 28, 29, 32, 33, 34, 35, 41, 42, 45, 46, 47, 54, 56, 58, 60, 65, 67, 68, 70, 75, 77, 78, 81, 85, 89, 92, 94, 95, 99, 100, 101, 106, 107, 108, 109, 111, 124, 125, 128, 129, 130, 132, 133, 135, 140, 141, 143, 145, 146, 147, 152, 154, 156, 158
Offset: 1

Views

Author

Klaus Brockhaus, Jul 15 2004

Keywords

Examples

			21 is the unique k such that k + (product of nonzero digits of k) = 23, hence 23 is a term.
		

Crossrefs

Programs

  • Mathematica
    f[n_] := Block[{s = Sort[ IntegerDigits[n]]}, While[ s[[1]] == 0, s = Drop[s, 1]]; n + Times @@ s]; t = Table[0, {200}]; Do[ a = f[n]; If[a < 200, t[[a]]++ ], {n, 200}]; Select[ Range[ 200], t[[ # ]] == 1 &] (* Robert G. Wilson v, Jul 16 2004 *)
  • PARI
    addpnd(n)=local(k,s,d);k=n;s=1;while(k>0,d=divrem(k,10);k=d[1];s=s*max(1,d[2]));n+s
    {c=1;z=160;v=vector(z);for(n=1,z+1,k=addpnd(n);if(k<=z,v[k]=v[k]+1));for(j=1,length(v),if(v[j]==c,print1(j,",")))}

A230099 a(n) = n + (product of digits of n).

Original entry on oeis.org

0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 20, 23, 26, 29, 32, 35, 38, 41, 44, 47, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 50, 56, 62, 68, 74, 80, 86, 92, 98, 104, 60, 67, 74, 81, 88, 95, 102, 109, 116, 123, 70, 78, 86, 94, 102, 110, 118, 126
Offset: 0

Views

Author

N. J. A. Sloane, Oct 12 2013

Keywords

Comments

A230099, A063114, A098736, A230101 are analogs of A092391 and A062028.

Crossrefs

Programs

  • Haskell
    a230099 n = a007954 n + n  -- Reinhard Zumkeller, Oct 13 2013
    
  • Maple
    with transforms; [seq(n+digprod(n), n=0..200)];
  • PARI
    a(n) = if (n, n + vecprod(digits(n)), 0); \\ Michel Marcus, Dec 18 2018
    
  • Python
    from math import prod
    def a(n): return n + prod(map(int, str(n)))
    print([a(n) for n in range(78)]) # Michael S. Branicky, Jan 09 2023

Formula

a(n) = n iff n contains a digit 0 (A011540). - Bernard Schott, Jul 31 2023

A096347 Least number with n preimages (or immediate predecessors) under f(n) = n + (product of nonzero digits of n).

Original entry on oeis.org

1, 2, 12, 102, 116, 1098, 2072, 1014, 101134, 11014, 1011098, 1003525, 41021255, 210110985, 403130555, 481104655, 4401225555, 4811125555, 86413249555, 39011218055
Offset: 0

Views

Author

Jason Earls, Jun 29 2004

Keywords

Comments

First occurrence of k in A096972.
a(20) > 10^11. [From Donovan Johnson, Nov 22 2009]

Examples

			a(3)=102 because 102 is the least number with three direct predecessors, 66: 66+6*6 = 102, 74: 74+7*4 = 102, 101: 101+1*1 = 102.
		

References

  • P. A. Loomis, An Introduction to Digit Product Sequences (see link).

Crossrefs

Extensions

a(8) to a(11) from Klaus Brockhaus, Jul 07 2004
a(12) from Robert G. Wilson v, Jul 15 2004
a(13)-a(19) from Donovan Johnson, Nov 22 2009

A063425 Unattainable numbers: integers not expressible as k + product of nonzero digits of k (A063114).

Original entry on oeis.org

1, 3, 5, 7, 9, 13, 15, 17, 19, 21, 25, 27, 30, 31, 36, 37, 39, 40, 43, 48, 49, 51, 52, 53, 57, 59, 61, 63, 64, 69, 71, 72, 73, 76, 79, 82, 83, 84, 87, 90, 91, 93, 96, 97, 103, 105, 113, 115, 117, 119, 121, 127, 131, 136, 137, 139, 148, 149, 151, 153, 157, 159, 163, 164
Offset: 1

Views

Author

Robert G. Wilson v, Aug 09 2001

Keywords

Crossrefs

Programs

  • Mathematica
    f[n_] := Block[{s = Sort[ IntegerDigits[n]]}, While[ s[[1]] == 0, s = Drop[s, 1]]; n + Times @@ s]; t = Table[0, {200}]; Do[ a = f[n]; If[a < 200, t[[a]]++ ], {n, 200}]; Select[ Range[ 200], t[[ # ]] == 0 &] (* Robert G. Wilson v, Jul 16 2004 *)

A063112 a(1) = 1; a(n+1) = a(n) + product of nonzero digits of a(n) when written in base 3. Display sequence in base 3.

Original entry on oeis.org

1, 2, 11, 12, 21, 100, 101, 102, 111, 112, 121, 200, 202, 220, 1001, 1002, 1011, 1012, 1021, 1100, 1101, 1102, 1111, 1112, 1121, 1200, 1202, 1220, 2001, 2010, 2012, 2100, 2102, 2120, 2201, 2212, 10011, 10012, 10021, 10100, 10101, 10102, 10111, 10112
Offset: 1

Views

Author

N. J. A. Sloane, Aug 08 2001

Keywords

Crossrefs

Programs

  • PARI
    baseE(x, b)= { local(d, e, f); e=0; f=1; while (x>0, d=x-b*(x\b); x\=b; e+=d*f; f*=10); return(e) }
    ProdNzD(x)= { local(d, p); p=1; while (x>9, d=x-10*(x\10); if (d, p*=d); x\=10); return(p*x) }
    { for (n=1, 1000, if (n>1, a=baseE(b+= ProdNzD(a), 3), a=1; b=1); write("b063112.txt", n, " ", a) ) } \\ Harry J. Smith, Aug 19 2009

Extensions

More terms from Vladeta Jovovic, Aug 10 2001

A063113 a(1) = 1; a(n+1) = a(n) + product of nonzero digits of a(n) when written in base 3. But display sequence in base 10.

Original entry on oeis.org

1, 2, 4, 5, 7, 9, 10, 11, 13, 14, 16, 18, 20, 24, 28, 29, 31, 32, 34, 36, 37, 38, 40, 41, 43, 45, 47, 51, 55, 57, 59, 63, 65, 69, 73, 77, 85, 86, 88, 90, 91, 92, 94, 95, 97, 99, 101, 105, 109, 110, 112, 113, 115, 117, 118, 119, 121, 122, 124, 126, 128, 132, 136, 138
Offset: 1

Views

Author

N. J. A. Sloane, Aug 08 2001

Keywords

Crossrefs

Programs

  • Mathematica
    f[n_Integer] := (a = Sort[ IntegerDigits[n, 3]]; While[ a[[1]] == 0, a = Delete[a, 1]]; n + Apply[ Times, a] ); NestList[f, 1, 65]
  • PARI
    baseE(x, b)= { local(d,e,f); e=0; f=1; while (x>0, d=x-b*(x\b); x\=b; e+=d*f; f*=10); return(e) }
    ProdNzD(x)= { local(d,p); p=1; while (x>9, d=x-10*(x\10); if (d, p*=d); x\=10); return(p*x) }
    { for (n=1, 1000, if (n>1, a=baseE(b+= ProdNzD(a), 3), a=1; b=1); write("b063113.txt", n, " ", b) ) } \\ Harry J. Smith, Aug 19 2009

Extensions

More terms from Robert G. Wilson v, Aug 09 2001

A230102 a(0)=1; thereafter a(n+1) = a(n) + (product of digits of a(n)).

Original entry on oeis.org

1, 2, 4, 8, 16, 22, 26, 38, 62, 74, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102
Offset: 0

Views

Author

N. J. A. Sloane, Oct 12 2013

Keywords

Comments

Never gets above 102.

Crossrefs

Programs

  • Haskell
    a230102 n = a230102_list !! n
    a230102_list = iterate a230099 1  -- Reinhard Zumkeller, Oct 13 2013
  • Mathematica
    NestList[#+Times@@IntegerDigits[#]&,1,50] (* Harvey P. Dale, Jul 30 2023 *)

A232485 a(1) = 3; thereafter a(n+1) = a(n) + product of digits of a(n).

Original entry on oeis.org

3, 6, 12, 14, 18, 26, 38, 62, 74, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102, 102
Offset: 1

Views

Author

N. J. A. Sloane, Nov 29 2013

Keywords

References

  • GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 36.

Crossrefs

Programs

  • Mathematica
    NestList[#+Times@@IntegerDigits[#]&,3,70] (* Harvey P. Dale, Jul 02 2017 *)
Showing 1-10 of 23 results. Next