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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A232486 a(1) = 3; thereafter a(n+1) = a(n) + product of nonzero digits of a(n).

Original entry on oeis.org

3, 6, 12, 14, 18, 26, 38, 62, 74, 102, 104, 108, 116, 122, 126, 138, 162, 174, 202, 206, 218, 234, 258, 338, 410, 414, 430, 442, 474, 586, 826, 922, 958, 1318, 1342, 1366, 1474, 1586, 1826, 1922, 1958, 2318, 2366, 2582, 2742, 2854, 3174, 3258, 3498, 4362, 4506
Offset: 1

Views

Author

N. J. A. Sloane, Nov 29 2013

Keywords

Crossrefs

Programs

  • Maple
    f:=proc(n) local t1,t2,i;
    t1:=convert(n,base,10);
    t2:=1;
    for i from 1 to nops(t1) do if t1[i] <> 0 then t2:=t2*t1[i]; fi; od;
    t2; end;
    g:=n->n+f(n);
    t1:=[3];
    for n from 1 to 50 do t1:=[op(t1),g(t1[nops(t1)])]; od:
    t1;

A232488 a(1) = 7; a(n+1) = a(n) + product of nonzero digits of a(n).

Original entry on oeis.org

7, 14, 18, 26, 38, 62, 74, 102, 104, 108, 116, 122, 126, 138, 162, 174, 202, 206, 218, 234, 258, 338, 410, 414, 430, 442, 474, 586, 826, 922, 958, 1318, 1342, 1366, 1474, 1586, 1826, 1922, 1958, 2318, 2366, 2582, 2742, 2854, 3174, 3258, 3498, 4362, 4506, 4626, 4914
Offset: 1

Views

Author

N. J. A. Sloane, Nov 29 2013

Keywords

Crossrefs

Programs

  • Maple
    See A232486.
  • Mathematica
    nxt[n_]:=n+Times@@Select[IntegerDigits[n],#!=0&]; NestList[nxt,7,50] (* Harvey P. Dale, Jun 13 2015 *)

A096972 Number of preimages of n (or immediate predecessors) under map f(k) = k + (product of nonzero digits of k).

Original entry on oeis.org

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, 0, 2, 0
Offset: 1

Views

Author

Robert G. Wilson v, Jul 16 2004

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, {111}]; Do[ t[[f [n]]]++, {n, 111}]; Table[ t[[n]], {n, 105}]

A232487 a(1) = 5; a(n+1) = a(n) + product of nonzero digits of a(n).

Original entry on oeis.org

5, 10, 11, 12, 14, 18, 26, 38, 62, 74, 102, 104, 108, 116, 122, 126, 138, 162, 174, 202, 206, 218, 234, 258, 338, 410, 414, 430, 442, 474, 586, 826, 922, 958, 1318, 1342, 1366, 1474, 1586, 1826, 1922, 1958, 2318, 2366, 2582, 2742, 2854, 3174, 3258, 3498, 4362
Offset: 1

Views

Author

N. J. A. Sloane, Nov 29 2013

Keywords

Crossrefs

Programs

  • Maple
    See A232486.
  • Mathematica
    NestList[#+Times@@Select[IntegerDigits[#],#>0&]&,5,50] (* Harvey P. Dale, Jul 07 2020 *)

A096729 Where records occur in A096287.

Original entry on oeis.org

1, 3, 5, 21, 37, 49, 51, 63, 4447, 5954, 6577, 9590, 12362, 38657, 42529, 42723, 154619, 158367, 512437, 965489, 978547, 1042723, 2377596, 2458779, 2687592, 2729784, 2976847, 2995687, 3233341, 3271507, 3378978, 3438666, 3447618
Offset: 1

Views

Author

Klaus Brockhaus and Jason Earls, Jul 06 2004

Keywords

Comments

The records are given in A096728.

Examples

			A096287(21) = 10 is the fourth record, so A096729(4) = 21.
		

Crossrefs

Extensions

a(23)-a(33) from Donovan Johnson, Nov 22 2009

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

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

A096728 Records in A096287.

Original entry on oeis.org

0, 5, 6, 10, 15, 16, 17, 322, 472, 474, 476, 487, 495, 894, 898, 900, 1437, 1443, 1456, 1459, 1460, 1461, 2594, 2653, 2661, 2674, 2899, 2900, 2905, 2907, 2908, 2915, 2919
Offset: 1

Views

Author

Klaus Brockhaus and Jason Earls, Jul 06 2004

Keywords

Comments

Numbers n such that A096287(n) is a record are given in A096729.

Examples

			A096287(5) = 6 and A096287(k) < 6 for k < 5, hence 6 is a term.
		

Crossrefs

Extensions

a(23)-a(33) from Donovan Johnson, Nov 22 2009

A248078 a(1) = 1; a(n+1) = a(n) + product of digits of a(n) + sum of digits of a(n).

Original entry on oeis.org

1, 3, 9, 27, 50, 55, 90, 99, 198, 288, 434, 493, 617, 673, 815, 869, 1324, 1358, 1495, 1694, 1930, 1943, 2068, 2084, 2098, 2117, 2142, 2167, 2267, 2452, 2545, 2761, 2861, 2974, 3500, 3508, 3524, 3658, 4400, 4408, 4424, 4566, 5307, 5322, 5394, 5955, 7104, 7116
Offset: 1

Views

Author

Gil Broussard, Sep 30 2014

Keywords

Comments

Unlike A063108, this sequence includes in its formula the digit 0 in the product of digits of a(n).

Examples

			Given a(5)=50, then a(6)=50+(5+0)+(5*0)=55.
		

Crossrefs

Programs

  • Maple
    f:= proc(x) local L;
      L:= convert(x,base,10);
      x + convert(L,`+`)+convert(L,`*`)
    end proc:
    A[1]:= 1:
    for n from 2 to 100 do A[n]:= f(A[n-1]) od:
    seq(A[i],i=1..100); # Robert Israel, Jun 25 2019
  • Mathematica
    NestList[#+Total[IntegerDigits[#]]+Times@@IntegerDigits[#]&,1,50] (* Harvey P. Dale, Sep 11 2019 *)
  • PARI
    lista(nn) = {prev = 1; print1(prev, ", "); for (n=1, nn, d = digits(prev); prev += sumdigits(prev) + prod(k=1, #d, d[k]); print1(prev, ", "););} \\ Michel Marcus, Oct 01 2014

A273913 Consider the sequence b(k) with initial values b(1) = 1 and b(2) = n and satisfying b(k) = b(k-1) + Pd(b(k-2)), where Pd(x) is the product of the digits of x. Then b(k) eventually becomes constant, and this constant is a(n).

Original entry on oeis.org

1902, 1902, 730, 230, 550, 420, 502, 1902, 2150, 1074, 1074, 1074, 1902, 1902, 8170, 730, 550, 730, 600, 230, 80, 230, 470, 550, 1074, 4045, 4990, 180, 230, 106, 90, 4990, 1062, 102, 902, 1230, 730, 108, 1406, 1017, 1410, 630, 2038, 505, 230, 1810, 150, 2306, 630
Offset: 1

Views

Author

Paolo P. Lava, Jun 17 2016

Keywords

Comments

Maximum value in the first 10^5 terms is a(6874) = 209875, from b(128) on.
First n's whose last repetitive number of the sequence b(k) is a multiple: 1, 2, 5, 6, 34, 42, 135, 195, 460, 893, 2370, 4230, 7165, 237945.

Examples

			b(1) = 1, b(2) = 7. Then:
b(3) = 7 + Pd(1) = 7+1 = 8; b(4) = 8 + Pd(7) = 8+7 = 15;
b(5) = 15 + Pd(8) = 15+8 = 23; b(6) = 23 + Pd(15) = 23+5 = 28;
b(7) = 28 + Pd(23) = 28+6 = 34; b(8) = 34 + Pd(28) = 34+16 = 50;
…
b(19) = 270 + Pd(214) = 270+8 = 278; b(20) = 278 + Pd(270) = 278+0 = 278;
b(21) = 278 + Pd(278) = 278+112 = 390; b(22) = 390 + Pd(278) = 390+112 = 502;
b(23) = 502 + Pd(502) = 502+0 = 502; therefore a(7) = 502.
		

Crossrefs

Programs

  • Maple
    with(numtheory); T:=proc(w) local x, y, z; x:=w; y:=1;
    for z from 1 to ilog10(x)+1 do y:=y*(x mod 10); x:=trunc(x/10); od; y; end:
    P:=proc(q) local a1,a2,a3,n; for n from 1 to q do a1:=1; a2:=n; a3:=T(a1)+a2;
    while not (a1=a2 and a2=a3) do a1:=a2; a2:=a3; a3:=T(a1)+a2; od;  print(a1);
    od; end: P(10^7);
  • Mathematica
    a[n_] := Block[{b=0, c=1, d=n, p}, While[! (b == c == d), b=c; p = Times @@ IntegerDigits@ c; c = d; d += p]; d]; Array[a, 50] (* Giovanni Resta, Jun 20 2016 *)
  • PARI
    pd(n) = my(d=digits(n)); prod(k=1, #d, d[k]);
    a(n) = {ba = 1; bb = n; bc = bb + pd(ba); while (!((ba ==bb) && (bc == bb)), newb = bb + pd(ba); ba = bb; bb = bc; bc = bb + pd(ba);); bc;} \\ Michel Marcus, Jun 20 2016
Previous Showing 11-20 of 23 results. Next