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.

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A096929 Numbers n for which there are exactly eight k such that n = k + (product of nonzero digits of k).

Original entry on oeis.org

101134, 101180, 101642, 108305, 204205, 216425, 220145, 220725, 231014, 271855, 283055, 291705, 300180, 301205, 302125, 303555, 330776, 405555, 442055, 442395, 464255, 492055, 604425, 621136, 691865, 702145, 711486, 723205, 733585, 784985
Offset: 1

Views

Author

Klaus Brockhaus, Jul 15 2004

Keywords

Examples

			88846, 97354, 98254, 99514, 100954, 101078, 101086 and 101131 are the only eight k such that k + (product of nonzero digits of k) = 101134, hence 101134 is a term.
		

Crossrefs

Programs

  • PARI
    {c=8;z=800000;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,",")))} \\for function addpnd see A096922

A096923 Numbers n for which there are exactly two k such that n = k + (product of nonzero digits of k).

Original entry on oeis.org

12, 14, 16, 18, 22, 26, 38, 44, 50, 55, 62, 66, 74, 80, 86, 88, 98, 104, 112, 114, 120, 122, 123, 138, 142, 144, 155, 160, 162, 166, 170, 174, 186, 188, 198, 209, 210, 212, 218, 224, 230, 237, 240, 250, 258, 261, 265, 285, 286, 294, 303, 308, 314, 316, 326, 327
Offset: 1

Views

Author

Klaus Brockhaus, Jul 15 2004

Keywords

Examples

			18 and 22 are the only two k such that k + (product of nonzero digits of k) = 26, hence 26 is a term.
		

Crossrefs

Programs

  • Mathematica
    knzd[n_]:=n+Times@@Select[IntegerDigits[n],#!=0&]; Sort[Transpose[ Select[ Tally[ Array[ knzd,400]],Last[#]==2&]][[1]]] (* Harvey P. Dale, Nov 05 2013 *)
  • PARI
    {c=2;z=330;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,",")))} \\for function addpnd see A096922

A096930 Numbers n for which there are exactly nine k such that n = k + (product of nonzero digits of k).

Original entry on oeis.org

11014, 100774, 111014, 412055, 510142, 511146, 633296, 931395, 983025, 1008305, 1011125, 1031414, 1100774, 1101642, 1108305, 1111014, 1412055, 1510142, 1511146, 1633296, 1931395, 1983025, 2011125, 2011305, 2012725, 2110145
Offset: 1

Views

Author

Klaus Brockhaus, Jul 15 2004

Keywords

Examples

			88486, 96454, 99073, 99154, 99316, 100594, 100654, 100718 and 100732 are the only nine k such that k + (product of nonzero digits of k) = 100774, hence 100774 is a term.
		

Crossrefs

Programs

  • Mathematica
    Select[Tally[Table[n+Times@@DeleteCases[IntegerDigits[n],0],{n, 2111000}]],#[[2]]==9&][[All,1]]//Sort (* Harvey P. Dale, Sep 15 2019 *)
  • PARI
    {c=9;z=2120000;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,",")))} \\for function addpnd see A096922

A063543 a(n) = n - product of the nonzero digits of n.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 18, 19, 18, 17, 16, 15, 14, 13, 12, 11, 27, 28, 26, 24, 22, 20, 18, 16, 14, 12, 36, 37, 34, 31, 28, 25, 22, 19, 16, 13, 45, 46, 42, 38, 34, 30, 26, 22, 18, 14, 54, 55, 50, 45, 40, 35, 30, 25, 20, 15, 63, 64, 58
Offset: 1

Views

Author

N. J. A. Sloane, Aug 14 2001

Keywords

Comments

The graph somewhat resembles wisteria flowers.

Examples

			a(20) = 20 - 2 = 18.
		

Crossrefs

Programs

  • Magma
    [n - &*[a: k in [1..#Intseq(n)] | a ne 0 where a is Intseq(n)[k]]: n in [1..100]]; // Marius A. Burtea, Sep 16 2019
  • Maple
    a:= n-> n-mul(i, i=subs(0=1, convert(n, base, 10))):
    seq(a(n), n=1..80);  # Alois P. Heinz, Aug 18 2019
  • Mathematica
    Table[n - Times@@DeleteCases[IntegerDigits[n], 0], {n, 70}] (* Alonso del Arte, Dec 15 2013 *)
  • PARI
    a(n) = my(d=select(x->(x!=0), digits(n))); n - vecprod(d); \\ Michel Marcus, Jan 13 2020
    
  • Python
    def a(n):
        digits = map(int, str(n))
        product = 1
        for d in digits:
            if d != 0:
                product *= d
        return n - product
    [a(n) for n in range(20)]
    # Elisabeth Zemack, Sep 16 2019; corrected by Fabio Somenzi, Jan 13 2020
    

Formula

a(n) = n - A051801(n).

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Aug 14 2001

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

A230106 Number of m such that m + (product of nonzero digits of m) equals n.

Original entry on oeis.org

0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 2, 0, 2, 0, 2, 0, 2, 0, 1, 0, 2, 1, 1, 0, 2, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 2, 0, 0, 1, 1, 0, 2, 1, 1, 1, 0, 0, 2, 0, 0, 0, 1, 2, 1, 0, 1, 0, 1, 0, 2, 0, 0, 1, 2, 1, 1, 0, 1, 0, 0, 0, 2, 1, 0, 1, 1, 0, 2, 1, 0, 0, 0, 1, 2, 0, 2, 1, 0, 0, 1, 0, 1, 1, 0, 0, 2, 1, 1, 1, 3
Offset: 0

Views

Author

N. J. A. Sloane, Oct 13 2013

Keywords

Comments

Number of times n appears in A063114.

Crossrefs

Programs

  • Maple
    # Maple code for A063114, A230106, A063425, A096922
    with(LinearAlgebra):
    read transforms; # to get digprod0
    M:=1000;
    lis1:=Array(0..M);
    lis2:=Array(0..M);
    ctmax:=4;
    for i from 0 to ctmax do ct[i]:=Array(0..M); od:
    for n from 0 to M do
    m:=n+digprod0(n);
    lis1[n]:=m;
    if (m <= M) then lis2[m]:=lis2[m]+1; fi;
    od:
    t1:=[seq(lis1[i],i=0..M)]; # A063114
    t2:=[seq(lis2[i],i=0..M)]; # A230106
    COMPl(t1); # A063425
    for i from 1 to M do h:=lis2[i];
    if h <= ctmax then ct[h]:=[op(ct[h]),i]; fi; od:
    len:=nops(ct[0]); [seq(ct[0][i],i=1..len)]; # A063425 again
    len:=nops(ct[1]); [seq(ct[1][i],i=1..len)]; # A096922

Extensions

a(1) corrected by Zak Seidov, Oct 24 2013

A233692 The smallest prime that produces a set of n primes such that every prime after the first one is equal to the previous plus the product of its nonzero digits.

Original entry on oeis.org

2, 23, 23, 239, 239, 239, 3413, 14249, 524219, 4167379, 324550981, 2589767209, 346333812907
Offset: 1

Views

Author

Carlos Rivera, Dec 14 2013

Keywords

Comments

This sequence was produced as solution to the problem 1270 of Claudio Meller's website (see link).

Examples

			For n=3, initial prime=23, set {23, 29, 47} because 23 -> 23+2*3=29 -> 29+2*9=47.
For n=2 to 9, the sets are
      23,     29;
      23,     29,     47;
     239,    293,    347,    431;
     239,    293,    347,    431,    443;
     239,    293,    347,    431,    443,    491;
    3413,   3449,   3881,   4073,   4157,   4297,   4801;
   14249,  14537,  14957,  16217,  16301,  16319,  16481,  16673;
  524219, 524939, 534659, 550859, 559859, 640859, 649499, 719483, 725531.
		

Crossrefs

Programs

  • PARI
    checkp(p, n) = {ok = isprime(p); for (i=1, n, print1(p, ", "); digs = digits(p); np = p + prod(i=1, #digs, if (d=digs[i], d, 1)); p = np;if (i != n, ok = ok && isprime(p));); ok;} \\ Michel Marcus, Dec 15 2013

Extensions

a(13) from Giovanni Resta, Dec 15 2013

A243140 Numbers n such that n appears in the sequence beginning with the digit-product of n and extended by adding successive digit-products.

Original entry on oeis.org

22, 26, 38, 55, 62, 88, 95, 102, 104, 108, 116, 122, 126, 138, 162, 174, 202, 206, 218, 234, 258, 410, 414, 430, 442, 474, 586, 826, 922, 1318, 1342, 1366, 1474, 1586, 1826, 1922, 1958, 2318, 2366, 2582, 2742, 3174, 3258, 3498, 4362
Offset: 1

Views

Author

Anthony Sand, May 30 2014

Keywords

Comments

Numbers n>9 with following property: form a sequence b(i) whose initial term is digit-product(n). Later terms are given by the rule that b(i) = b(i-1) + digit-product(b(i-1)) and n itself appears in the sequence.
The function digit-product(n) multiplies all nonzero digits of n (A051801). For example, digit-product(1230) = 1 * 2 * 3 = 6. The resultant sequence appears in A063114, n + product of nonzero digits of n.

Examples

			The digit-product sequence for 22 begins with digit-product(22)= 4, 4 + 4 = 8, 8 + 8 = 16, 16 + 6 = 22. Since this procedure returns to the initial number 22, it belongs here.
The digit-product sequence for 102 begins with 2, 2 + 2 = 4, 4 + 4 = 8, 8 + 8 = 16, 16 + 6 = 22, 22 + 4 = 26, 26 + 12 = 38, 38 + 24 = 62, 62 + 12 = 74, 74 + 28 = 102. Since this procedure returns to the initial number 102, it belongs here.
		

Crossrefs

Programs

  • PARI
    dp(n)=my(v=select(k->k>1,digits(n))); prod(i=1,#v,v[i])
    is(n)=my(t=dp(n)); until(t>=n, t+=dp(t)); t==n \\ Charles R Greathouse IV, Jun 05 2014

Formula

b(i) = b(i-1) + digit-product(b(i-1)).

A096355 Number of unattainables <= 10^n, where unattainables are A063425.

Original entry on oeis.org

5, 44, 429, 4069, 39433, 388459, 3855173, 38374875, 382644491, 3819130611
Offset: 1

Views

Author

Jason Earls, Jun 30 2004

Keywords

Crossrefs

Cf. A063114.

Extensions

a(9)-a(10) from Donovan Johnson, Jul 20 2010
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