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 15 results. Next

A342855 Numbers that contain a digit 0 (A011540) and that are divisible by their nonzero digits (A002796).

Original entry on oeis.org

10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 101, 102, 104, 105, 110, 120, 140, 150, 200, 202, 204, 208, 210, 220, 240, 250, 280, 300, 303, 306, 330, 360, 400, 404, 408, 420, 440, 480, 500, 505, 510, 520, 540, 550, 600, 606, 630, 660, 700, 707, 770, 800, 808, 840, 880, 900, 909, 990, 1000
Offset: 1

Views

Author

Bernard Schott, Mar 25 2021

Keywords

Comments

If m is a term, so is 10*m.

Examples

			208 = 2*104 = 8*26 is divisible by 2 and divisible by 8, 208 contains a digit 0, hence 208 is a term.
		

Crossrefs

Intersection of A002796 and A011540.

Programs

  • Mathematica
    q[n_] := MemberQ[(d = IntegerDigits[n]), 0] && AllTrue[d, # == 0 || Divisible[n, #] &]; Select[Range[1000], q] (* Amiram Eldar, Mar 25 2021 *)
  • PARI
    isok(m) = my(d=digits(m)); if (vecmin(d), return (0)); d = vecsort(select(x->(x > 0), d),,8); for (k=1, #d, if (m % d[k], return(0))); return(1); \\ Michel Marcus, Mar 29 2021

Formula

a(n) ~ 2520n. - Charles R Greathouse IV, Nov 25 2024

A007602 Numbers that are divisible by the product of their digits.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 15, 24, 36, 111, 112, 115, 128, 132, 135, 144, 175, 212, 216, 224, 312, 315, 384, 432, 612, 624, 672, 735, 816, 1111, 1112, 1113, 1115, 1116, 1131, 1176, 1184, 1197, 1212, 1296, 1311, 1332, 1344, 1416, 1575, 1715, 2112, 2144
Offset: 1

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Author

Keywords

Comments

These are called Zuckerman numbers to base 10. [So-named by J. J. Tattersall, after Herbert S. Zuckerman. - Charles R Greathouse IV, Jun 06 2017] - Howard Berman (howard_berman(AT)hotmail.com), Nov 09 2008
This sequence is a subsequence of A180484; the first member of A180484 that is not a member of A007602 is 1114. - D. S. McNeil, Sep 09 2010
Complement of A188643; A188642(a(n)) = 1; A038186 is a subsequence; A168046(a(n)) = 1: subsequence of A052382. - Reinhard Zumkeller, Apr 07 2011
The terms of n digits in the sequence, for n from 1 to 14, are 9, 5, 20, 40, 117, 285, 747, 1951, 5229, 13493, 35009, 91792, 239791, 628412, 1643144, 4314987. Empirically, the counts seem to grow as 0.858*2.62326^n. - Giovanni Resta, Jun 25 2017
De Koninck and Luca showed that the number of Zuckerman numbers below x is at least x^0.122 but at most x^0.863. - Tomohiro Yamada, Nov 17 2017
The quotients obtained when Zuckerman numbers are divided by the product of their digits are in A288069. - Bernard Schott, Mar 28 2021

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • James J. Tattersall, Elementary Number Theory in Nine Chapters (2005), 2nd Edition, p. 86 (see problems 44-45).

Crossrefs

Cf. A286590 (for factorial-base analog).
Subsequence of A002796, A034838, and A055471.

Programs

  • Haskell
    import Data.List (elemIndices)
    a007602 n = a007602_list !! (n-1)
    a007602_list = map succ $ elemIndices 1 $ map a188642 [1..]
    -- Reinhard Zumkeller, Apr 07 2011
    
  • Magma
    [ n: n in [1..2144] | not IsZero(&*Intseq(n)) and IsZero(n mod &*Intseq(n)) ];  // Bruno Berselli, May 28 2011
    
  • Maple
    filter:= proc(n)
    local p;
    p:= convert(convert(n,base,10),`*`);
    p <> 0 and n mod p = 0
    end proc;
    select(filter, [$1..10000]); # Robert Israel, Aug 24 2014
  • Mathematica
    zuckerQ[n_] := Module[{d = IntegerDigits[n], prod}, prod = Times @@ d; prod > 0 && Mod[n, prod] == 0]; Select[Range[5000], zuckerQ] (* Alonso del Arte, Aug 04 2004 *)
  • PARI
    for(n=1,10^5,d=digits(n);p=prod(i=1,#d,d[i]);if(p&&n%p==0,print1(n,", "))) \\ Derek Orr, Aug 25 2014
  • Python
    from operator import mul
    from functools import reduce
    A007602 = [n for n in range(1,10**5) if not (str(n).count('0') or n % reduce(mul, (int(d) for d in str(n))))] # Chai Wah Wu, Aug 25 2014
    

A034838 Numbers k that are divisible by every digit of k.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 15, 22, 24, 33, 36, 44, 48, 55, 66, 77, 88, 99, 111, 112, 115, 122, 124, 126, 128, 132, 135, 144, 155, 162, 168, 175, 184, 212, 216, 222, 224, 244, 248, 264, 288, 312, 315, 324, 333, 336, 366, 384, 396, 412, 424, 432, 444, 448
Offset: 1

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Author

Keywords

Comments

Subset of zeroless numbers A052382: Integers with at least one digit 0 (A011540) are excluded.
A128635(a(n)) = n.
Contains in particular all repdigits A010785 \ {0}. - M. F. Hasler, Jan 05 2020
The greatest term such that the digits are all different is the greatest Lynch-Bell number 9867312 = A115569(548) = A113028(10) [see Diophante link]. - Bernard Schott, Mar 18 2021
Named "nude numbers" by Katagiri (1982-83). - Amiram Eldar, Jun 26 2021

Examples

			36 is in the sequence because it is divisible by both 3 and 6.
48 is included because both 4 and 8 divide 48.
64 is not included because even though 4 divides 64, 6 does not.
		

References

  • Charles Ashbacher, Journal of Recreational Mathematics, Vol. 33 (2005), pp. 227. See problem number 2693.
  • Yoshinao Katagiri, Letter to the editor of the Journal of Recreational Mathematics, Vol. 15, No. 4 (1982-83).
  • Margaret J. Kenney and Stanley J. Bezuszka, Number Treasury 3: Investigations, Facts And Conjectures About More Than 100 Number Families, World Scientific, 2015, p. 175.
  • Thomas Koshy, Elementary Number Theory with Applications, Elsevier, 2007, p. 79.

Crossrefs

Intersection of A002796 (numbers divisible by each nonzero digit) and A052382 (zeroless numbers), or A002796 \ A011540 (numbers with digit 0).
Subsequence of A034709 (divisible by last digit).
Contains A007602 (multiples of the product of their digits) and subset A059405 (n is the product of its digits raised to positive powers), A225299 (divisible by square of each digit), and A066484 (n and its rotations are divisible by each digit).
Cf. A113028, A346267 (number of terms with n digits), A087140 (complement).
Supersequence of A115569 (with all different digits).

Programs

  • Haskell
    a034838 n = a034838_list !! (n-1)
    a034838_list = filter f a052382_list where
       f u = g u where
         g v = v == 0 || mod u d == 0 && g v' where (v',d) = divMod v 10
    -- Reinhard Zumkeller, Jun 15 2012, Dec 21 2011
    
  • Magma
    [n:n in [1..500]| not 0 in Intseq(n) and #[c:c in [1..#Intseq(n)]| n mod Intseq(n)[c] eq 0] eq #Intseq(n)] // Marius A. Burtea, Sep 12 2019
  • Maple
    a:=proc(n) local nn,j,b,bb: nn:=convert(n,base,10): for j from 1 to nops(nn) do b[j]:=n/nn[j] od: bb:=[seq(b[j],j=1..nops(nn))]: if map(floor,bb)=bb then n else fi end: 1,2,3,4,5,6,7,8,9,seq(seq(seq(a(100*m+10*n+k),k=1..9),n=1..9),m=0..6); # Emeric Deutsch
  • Mathematica
    divByEvryDigitQ[n_] := Block[{id = Union[IntegerDigits[n]]}, Union[ IntegerQ[ #] & /@ (n/id)] == {True}]; Select[ Range[ 487],  divByEvryDigitQ[#] &] (* Robert G. Wilson v, Jun 21 2005 *)
    Select[Range[500],FreeQ[IntegerDigits[#],0]&&AllTrue[#/ IntegerDigits[ #], IntegerQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Mar 31 2019 *)
  • PARI
    is(n)=my(v=vecsort(eval(Vec(Str(n))),,8)); if(v[1]==0, return(0)); for(i=1, #v, if(n%v[i], return(0))); 1 \\ Charles R Greathouse IV, Apr 17 2012
    
  • PARI
    is_A034838(n)=my(d=Set(digits(n)));d[1]&&!forstep(i=#d,1,-1,n%d[i]&&return) \\ M. F. Hasler, Jan 10 2016
    
  • Python
    A034838_list = []
    for g in range(1,4):
        for n in product('123456789',repeat=g):
            s = ''.join(n)
            m = int(s)
            if not any(m % int(d) for d in s):
                A034838_list.append(m) # Chai Wah Wu, Sep 18 2014
    
  • Python
    for n in range(10**3):
        s = str(n)
        if '0' not in s:
            c = 0
            for i in s:
                if n%int(i):
                    c += 1
                    break
            if not c:
                print(n,end=', ') # Derek Orr, Sep 19 2014
    
  • Python
    # finite automaton accepting sequence (see comments in A346267)
    from math import gcd
    def lcm(a, b): return a * b // gcd(a, b)
    def inF(q): return q[0]%q[1] == 0
    def delta(q, c): return ((10*q[0]+c)%2520, lcm(q[1], c))
    def ok(n):
        q = (0, 1)
        for c in map(int, str(n)):
            if c == 0: return False # computation dies
            else: q = delta(q, c)
        return inF(q)
    print(list(filter(ok, range(450)))) # Michael S. Branicky, Jul 18 2021
    

A067458 Sum of remainders when n is divided by its nonzero digits.

Original entry on oeis.org

0, 0, 0, 1, 2, 0, 4, 3, 2, 1, 0, 1, 0, 3, 0, 1, 2, 7, 4, 3, 0, 1, 2, 0, 3, 2, 0, 3, 8, 3, 0, 1, 2, 4, 0, 1, 6, 8, 0, 5, 0, 1, 2, 5, 6, 0, 3, 3, 5, 9, 0, 1, 2, 3, 4, 5, 0, 5, 6, 9, 0, 1, 2, 4, 6, 5, 10, 0, 7, 9, 0, 1, 2, 5, 4, 5, 8, 10, 0, 9, 0, 1, 2, 3, 6, 5, 6, 13, 10, 0, 0
Offset: 10

Views

Author

Amarnath Murthy, Feb 07 2002

Keywords

Comments

a(n) = 0 for 0 < n 10.
a(A002796(n)) = 0; a(A171492(n)) > 0. - Reinhard Zumkeller, Sep 24 2015

Examples

			a(14)= 2 as 1 divides 14 and 2 is the remainder obtained when 14 is divided by 4.
		

Crossrefs

Programs

  • Haskell
    a067458 n = f 0 n where
       f y 0 = y
       f y x = if d == 0 then f y x' else f (y + mod n d) x'
               where (x', d) = divMod x 10
    -- Reinhard Zumkeller, Sep 24 2015
  • Mathematica
    Table[Plus @@ Mod[n, Select[IntegerDigits[n], # != 0 &]], {n, 10, 100}]

Extensions

Edited and extended by Robert G. Wilson v, Feb 11 2002

A239213 Squares that are divisible by each of their nonzero digits.

Original entry on oeis.org

1, 4, 9, 36, 100, 144, 324, 400, 784, 900, 1024, 1296, 1444, 1764, 2304, 2500, 2916, 3600, 9216, 10000, 10404, 11664, 12100, 12996, 14400, 19044, 22500, 24336, 26244, 28224, 32400, 36864, 39204, 40000, 41616, 44100, 48400, 69696, 78400, 82944, 90000, 93636
Offset: 1

Views

Author

Colin Barker, Mar 12 2014

Keywords

Comments

Intersection of A000290 and A002796.

Examples

			39204 is in the sequence because 39204 is divisible by 3, 9, 2 and 4.
		

Crossrefs

Programs

  • Mathematica
    dnzQ[n_]:=And@@Divisible[n,Select[IntegerDigits[n],#!=0&]]; Select[ Range[ 500]^2,dnzQ] (* Harvey P. Dale, Dec 04 2014 *)
  • PARI
    isOK(n) = my(v=vecsort(digits(n^2), , 8)); for(i=1+(v[1]==0), #v, if(n^2%v[i], return(0))); 1
    s=[]; for(n=1, 1000, if(isOK(n), s=concat(s, n^2))); s

A239222 Cubes that are divisible by each of their nonzero digits.

Original entry on oeis.org

1, 8, 216, 1000, 2744, 8000, 13824, 74088, 125000, 216000, 512000, 1000000, 1061208, 2000376, 2299968, 2744000, 4741632, 5832000, 8000000, 8242408, 8489664, 9261000, 10941048, 12812904, 13824000, 14886936, 16003008, 19683000, 34012224, 40001688, 42144192
Offset: 1

Views

Author

Colin Barker, Mar 12 2014

Keywords

Comments

Intersection of A000578 and A002796.

Examples

			74088 is in the sequence because 74088 is divisible by 4, 7 and 8.
		

Crossrefs

Programs

  • Mathematica
    dedQ[n_]:=And@@Divisible[n,Select[IntegerDigits[n],#>0&]]; Select[ Range[ 400]^3, dedQ] (* Harvey P. Dale, Apr 25 2015 *)
  • PARI
    isOK(n) = my(v=vecsort(digits(n^3), , 8)); for(i=1+(v[1]==0), #v, if(n^3%v[i], return(0))); 1
    s=[]; for(n=1, 1000, if(isOK(n), s=concat(s, n^3))); s

Formula

a(n) = A239221^(n)^3. - Michel Marcus, Mar 19 2014

A078546 LCM of n and its nonzero decimal digits.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 39, 28, 15, 48, 119, 72, 171, 20, 42, 22, 138, 24, 50, 78, 378, 56, 522, 30, 93, 96, 33, 204, 105, 36, 777, 456, 117, 40, 164, 84, 516, 44, 180, 276, 1316, 48, 1764, 50, 255, 260, 795, 540, 55, 840, 1995, 1160, 2655, 60, 366, 186
Offset: 1

Views

Author

Labos Elemer, Dec 05 2002

Keywords

Examples

			n=13: lcm(13,1,3) = 39 = a(13); a(x)=x if x is divisible by each nonzero digits, i.e., if x in A002796.
		

Crossrefs

Programs

  • Mathematica
    lc[x_] := Apply[LCM, DeleteCases[IntegerDigits[x], 0]] Table[LCM[lc[w], w], {w, 1, 128}] NOT
  • PARI
    lcnzd(n) = lcm(select(x->(x!=0), digits(n)));
    a(n) = lcm(n, lcnzd(n)); \\ Michel Marcus, Mar 18 2018

Formula

a(n) = lcm(n, A052429(n)).

A171492 Numbers that are not divisible by each of their nonzero decimal digits.

Original entry on oeis.org

13, 14, 16, 17, 18, 19, 21, 23, 25, 26, 27, 28, 29, 31, 32, 34, 35, 37, 38, 39, 41, 42, 43, 45, 46, 47, 49, 51, 52, 53, 54, 56, 57, 58, 59, 61, 62, 63, 64, 65, 67, 68, 69, 71, 72, 73, 74, 75, 76, 78, 79, 81, 82, 83, 84, 85, 86, 87, 89, 91, 92, 93, 94, 95, 96, 97, 98, 103, 106
Offset: 1

Views

Author

Jaroslav Krizek, Dec 10 2009

Keywords

Comments

Complement of A002796.
A067458(a(n)) > 0. - Reinhard Zumkeller, Sep 24 2015

Crossrefs

Programs

  • Haskell
    import Data.List (nub, sort); import Data.Char (digitToInt)
    a171492 n = a171492_list !! (n-1)
    a171492_list = filter f [1..] where
       f x = any ((> 0) . mod x) ds where
         ds = map digitToInt (if c == '0' then cs else cs')
         cs'@(c:cs) = nub $ sort $ show x
    -- Reinhard Zumkeller, Jan 01 2014
    
  • Magma
    sol:=[];for k in [1..120] do a:=Set(Intseq(k)) diff {0}; if #[c:c in a|IsIntegral(k/c)] ne #a then; Append(~sol,k); end if; end for; sol; // Marius A. Burtea, Sep 09 2019
  • Mathematica
    a[c_]:=Module[{b=DeleteCases[IntegerDigits[c], 0]}, !And@@Divisible[c, b]]; Select[Range[250], a] (* Metin Sariyar, Sep 14 2019 *)

Formula

a(n) ~ k*n, where k = 2520/2519 = 1.00039.... - Charles R Greathouse IV, Feb 13 2017

A237851 a(1)=1; a(n) is the smallest integer not yet in the sequence divisible by all nonzero digits of a(n-1).

Original entry on oeis.org

1, 2, 4, 8, 16, 6, 12, 10, 3, 9, 18, 24, 20, 14, 28, 32, 30, 15, 5, 25, 40, 36, 42, 44, 48, 56, 60, 54, 80, 64, 72, 70, 7, 21, 22, 26, 66, 78, 112, 34, 84, 88, 96, 90, 27, 98, 144, 52, 50, 35, 45, 100, 11, 13, 33, 39, 63, 102, 38, 120, 46, 108, 104, 68, 168
Offset: 1

Views

Author

Eric Angelini, Feb 14 2014

Keywords

Comments

A permutation of the naturals with inverse A237860.
If a(n) is a prime greater than 7 then no digit of a(n-1) is greater than 1, cf. A007088.

Crossrefs

Programs

  • Haskell
    import Data.List (nub, sort, delete)
    a237851 n = a237851_list !! (n-1)
    a237851_list = 1 : f 1 [2..] where
       f x zs = g zs where
         g (u:us) | all ((== 0) . (mod u)) ds = u : f u (delete u zs)
                  | otherwise = g us
                  where ds = dropWhile (<= 1) $
                             sort $ nub $ map (read . return) $ show x
    -- Reinhard Zumkeller, Feb 14 2014
  • Mathematica
    a[1] = 1;
    a[n_] := a[n] = For[k = 1, True, k++, If[FreeQ[Array[a, n-1], k], If[ AllTrue[Select[IntegerDigits[a[n-1]], #>0&] // Union, Divisible[k, #]&], Return[k]]]];
    a /@ Range[100] (* Jean-François Alcover, Nov 26 2019 *)

A078547 a(n) = lcm(n, A052429(n)) - n.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 26, 14, 0, 32, 102, 54, 152, 0, 21, 0, 115, 0, 25, 52, 351, 28, 493, 0, 62, 64, 0, 170, 70, 0, 740, 418, 78, 0, 123, 42, 473, 0, 135, 230, 1269, 0, 1715, 0, 204, 208, 742, 486, 0, 784, 1938, 1102, 2596, 0, 305, 124, 63, 128, 325, 0
Offset: 1

Views

Author

Labos Elemer, Dec 05 2002

Keywords

Comments

a(n)=0 if n is divisible by each nonzero digit, i.e., if n in A002796.

Crossrefs

Programs

  • Mathematica
    lc[x_] := Apply[LCM, DeleteCases[IntegerDigits[x], 0]] Table[LCM[lc[w], w]-w, {w, 1, 128}]
  • PARI
    lcnzd(n) = lcm(select(x->(x!=0), digits(n)));
    a(n) = lcm(n, lcnzd(n)) - n; \\ Michel Marcus, Mar 18 2018
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