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 1-8 of 8 results.

A029783 Exclusionary squares: numbers n such that no digit of n is present in n^2.

Original entry on oeis.org

2, 3, 4, 7, 8, 9, 17, 18, 22, 24, 29, 33, 34, 38, 39, 44, 47, 53, 54, 57, 58, 59, 62, 67, 72, 77, 79, 84, 88, 92, 94, 144, 157, 158, 173, 187, 188, 192, 194, 209, 212, 224, 237, 238, 244, 247, 253, 257, 259, 307, 313, 314, 333, 334, 338, 349, 353, 359
Offset: 1

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Author

Keywords

Comments

Complement of A189056; A076493(a(n)) = 0. - Reinhard Zumkeller, Apr 16 2011
A258682(a(n)) = a(n)^2. - Reinhard Zumkeller, Jun 07 2015
a(78) = 567 and a(112) = 854 are the only two numbers k such that the equation k^2 = m uses only once each of the digits 1 to 9 (reference David Wells). Exactly: 567^2 = 321489, and, 854^2 = 729316 (see A059930). - Bernard Schott, Jan 28 2021

Examples

			From _M. F. Hasler_, Oct 16 2018: (Start)
It is easy to construct infinite subsequences of the form S(a,b)(n) = a*R(n) + b, where R(n) = (10^n-1)/9 is the repunit of length n. Among these are:
S(3,0) = (3, 33, 333, ...), S(3,1) = (4, 34, 334, 3334, ...), S(3,5) = (8, 38, 338, ...), also b = 26, 44, 434, ... (with a = 3); S(6,1) = (7, 67, 667, ...), S(6,6) = (72, 672, 6672, ...) (excluding n=1), S(6,7) = (673, 6673, ...) (excluding also n=2 here), S(6,-7) = (59, 659, 6659, ...), and others. (End)
		

References

  • Clifford A. Pickover, A Passion for Mathematics, Wiley, 2005; see p. 60.
  • David Wells, The Penguin Dictionary of Curious and Interesting Numbers, Revised Edition, 1997, page 144, entry 567.

Crossrefs

Cf. A059930 (n and n^2 use different digits), A112736 (numbers whose squares are exclusionary).

Programs

  • Haskell
    a029783 n = a029783_list !! (n-1)
    a029783_list = filter (\x -> a258682 x == x ^ 2) [1..]
    -- Reinhard Zumkeller, Jun 07 2015, Apr 16 2011
    
  • Mathematica
    Select[Range[1000], Intersection[IntegerDigits[ # ], IntegerDigits[ #^2]] == {} &] (* Tanya Khovanova, Dec 25 2006 *)
  • PARI
    is_A029783(n)=!#setintersect(Set(digits(n)),Set(digits(n^2))) \\ M. F. Hasler, Oct 16 2018
    
  • Python
    # see linked program
    
  • Python
    from itertools import count, islice
    def A029783_gen(startvalue=0): # generator of terms >= startvalue
        return filter(lambda n:not set(str(n))&set(str(n**2)),count(max(startvalue,0)))
    A029783_list = list(islice(A029783_gen(),30)) # Chai Wah Wu, Feb 12 2023

Extensions

Definition slightly reworded at the suggestion of Franklin T. Adams-Watters by M. F. Hasler, Oct 16 2018

A111116 Numbers n such that digits of n are not present in n^4.

Original entry on oeis.org

2, 3, 4, 7, 8, 9, 24, 27, 28, 32, 33, 42, 52, 53, 58, 59, 67, 77, 88, 89, 93, 202, 203, 258, 284, 303, 324, 329, 377, 383, 422, 669, 818, 832, 843, 878, 882, 887, 949, 2027, 2042, 2673, 3144, 3222, 3253, 3302, 3308, 3737, 3773, 3953, 3979, 3983, 4779, 5353, 5669
Offset: 1

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Author

Lekraj Beedassy, Oct 15 2005

Keywords

Comments

The number of k-digit numbers for which this occurs is: 6,15,18,32,21,14,20,...

Crossrefs

For the corresponding n^4, see A113316.

Programs

  • Mathematica
    Select[Range[6000], Intersection[IntegerDigits[ # ], IntegerDigits[ #^4]] == {} &] (* Ray Chandler, Oct 17 2005 *)
    fQ[n_] := Intersection[ Union[ IntegerDigits[n]], Union[ IntegerDigits[n^4]]] == {}; Select[ Range[ 5887], fQ[ # ] &] (* Robert G. Wilson v *)
  • Python
    A111116_list = [n for n in range(1,10**6) if set(str(n)) & set(str(n**4)) == set()]
    # Chai Wah Wu, Jan 05 2015

Extensions

Corrected and extended by Robert G. Wilson v and Ray Chandler, Oct 17 2005

A113316 Fourth powers m^4 none of whose digits are present in their corresponding roots m.

Original entry on oeis.org

16, 81, 256, 2401, 4096, 6561, 331776, 531441, 614656, 1048576, 1185921, 3111696, 7311616, 7890481, 11316496, 12117361, 20151121, 35153041, 59969536, 62742241, 74805201, 1664966416, 1698181681, 4430766096, 6505390336, 8428892481
Offset: 1

Views

Author

Lekraj Beedassy, Oct 26 2005

Keywords

Comments

For the associated root m, see A111116.

Crossrefs

Programs

  • Mathematica
    Select[Range[350]^4,Intersection[IntegerDigits[#], IntegerDigits[ Surd[ #,4]]] =={}&] (* Harvey P. Dale, Dec 19 2015 *)

A029784 Squares such that digits of sqrt(n) are not present in n.

Original entry on oeis.org

4, 9, 16, 49, 64, 81, 289, 324, 484, 576, 841, 1089, 1156, 1444, 1521, 1936, 2209, 2809, 2916, 3249, 3364, 3481, 3844, 4489, 5184, 5929, 6241, 7056, 7744, 8464, 8836, 20736, 24649, 24964, 29929, 34969, 35344, 36864, 37636, 43681, 44944, 50176, 56169, 56644
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[500], {} == Intersection @@ IntegerDigits[{#, #^2}] &]^2 (* Giovanni Resta, Aug 08 2018 *)

Formula

a(n) = A029783(n)^2. - Michel Marcus, Aug 08 2018

Extensions

More terms from Giovanni Resta, Aug 08 2018

A029786 Cubes such that digits of cube root of n are not present in n.

Original entry on oeis.org

8, 27, 343, 512, 10648, 19683, 79507, 103823, 110592, 140608, 148877, 250047, 314432, 456533, 778688, 3869893, 5088448, 5545233, 6539203, 6644672, 7077888, 10941048, 11089567, 16003008, 18191447, 27818127, 54010152, 67917312, 75686967, 86350888, 96071912
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[1000], {} == Intersection @@ IntegerDigits[{#, #^3}] &]^3 (* Giovanni Resta, Aug 08 2018 *)

Extensions

More terms from Giovanni Resta, Aug 08 2018

A030087 Primes such that digits of p do not appear in p^3.

Original entry on oeis.org

2, 3, 7, 43, 47, 53, 157, 223, 263, 487, 577, 587, 823, 4657, 5657, 6653, 7177, 8287, 9343, 26777, 36293, 46477, 58787, 72727, 75707, 176777, 363313, 530353, 566653, 959953, 1771787, 2525557, 2555353, 2626277, 3656363, 4414447, 7110707, 8448343, 20700077, 54475457, 71117177, 72722977, 135135113, 393321293, 457887457, 505053053, 672722627
Offset: 1

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Author

Patrick De Geest, Dec 11 1999

Keywords

Comments

Primes of sequence A029785. - Michel Marcus, Jan 04 2015

Examples

			2 and 2^3=8 have no digits in common, hence 2 is in the sequence.
		

Crossrefs

Cf. A029785 (digits of n are not present in n^3), A030086 (similar, with p^2), A253574 (similar, with p^4).

Programs

  • Mathematica
    Select[Prime[Range[1500000]], Intersection[IntegerDigits[#], IntegerDigits[#^3]]=={} &] (* Vincenzo Librandi, Jan 04 2015 *)
  • PARI
    lista(nn) = {forprime (n=1, nn, if (#setintersect(Set(vecsort(digits(n^3))), Set(vecsort(digits(n)))) == 0, print1(n, ", ")); ); } \\ Michel Marcus, Jan 04 2015
    
  • Python
    from sympy import isprime
    A030087_list = [n for n in range(1,10**6) if set(str(n)) & set(str(n**3)) == set() and isprime(n)]
    # Chai Wah Wu, Jan 05 2015

Extensions

Changed offset from 0 to 1 and more terms from Vincenzo Librandi, Jan 04 2015
a(40)-a(47) from Chai Wah Wu, Jan 05 2015

A112994 Numbers whose cubes are exclusionary: numbers k such that k has no repeated digits and k and k^3 have no digits in common.

Original entry on oeis.org

2, 3, 7, 8, 27, 43, 47, 48, 52, 53, 63, 68, 92, 157, 172, 187, 192, 263, 378, 408, 423, 458, 468, 478, 487, 527, 587, 608, 648, 692, 823, 843, 918, 1457, 1587, 1592, 4657, 4732, 5692, 6058, 6378, 7658
Offset: 1

Views

Author

Lekraj Beedassy, Oct 13 2005

Keywords

Comments

A number k with no repeated digits has an exclusionary cube k^3 if the latter is made up of digits not appearing in k. (This is a subsequence of A029785.) For the corresponding exclusionary cubes see A112993. Conjectured to be complete.
Data are complete: there are 42 terms. - Michael S. Branicky, Aug 27 2021

References

  • H. Ibstedt, Solution to Problem 2623, "Exclusionary Powers", pp. 346-9, Journal of Recreational Mathematics, vol. 32 No.4 2003-4, Baywood NY.
  • Clifford A. Pickover, A Passion for Mathematics, Wiley, 2005; see p. 60.

Crossrefs

Subsequence of A029785.
The corresponding cubes are in A112993.

Programs

  • Mathematica
    Select[Range[8000],Max[DigitCount[#]]==1&&Intersection[IntegerDigits[ #],IntegerDigits[#^3]]=={}&] (* Harvey P. Dale, Sep 06 2021 *)
  • PARI
    isok(n) = my(digs = digits(n)); (#digs == #Set(digs)) && (#setintersect(Set(digs), Set(digits(n^3))) == 0); \\ Michel Marcus, Oct 26 2013
    
  • Python
    def ok(n):
        s = str(n)
        return len(s) == len(set(s)) and set(s) & set(str(n**3)) == set()
    print([k for k in range(7659) if ok(k)]) # Michael S. Branicky, Aug 27 2021
    
  • Python
    # version for verifying full sequence
    from itertools import permutations
    def no_repeated_digits():
        for d in range(1, 11):
            for p in permutations("0123456789", d):
                if p[0] == '0': continue
                yield int("".join(p))
    def afull():
        alst = []
        for k in no_repeated_digits():
            if set(str(k)) & set(str(k**3)) == set():
                alst.append(k)
        return alst
    print(afull()) # Michael S. Branicky, Aug 27 2021

Extensions

Missing term 468 added by N. J. A. Sloane, May 22 2008
Definition clarified by Harvey P. Dale, Sep 06 2021

A247883 Consecutive exclusionary cubes: Digits of n are not present in n^3 and digits of n+1 are not present in (n+1)^3.

Original entry on oeis.org

2, 7, 47, 52, 187, 222, 477, 587, 5522, 6777
Offset: 1

Views

Author

Derek Orr, Sep 25 2014

Keywords

Comments

If it exists, a(11) > 10^7.
All terms == 2 (mod 5). - Robert Israel, Mar 10 2025

Crossrefs

Cf. A029785.

Programs

  • Maple
    filter:= proc(n) convert(convert(n,base,10),set) intersect convert(convert(n^3,base,10),set) = {} end proc:
    select(t -> filter(t) and filter(t+1), [seq(i,i=2..10^6, 5)]); # Robert Israel, Mar 10 2025
  • PARI
    for(n=1,10^6,s=digits(n);t=digits(n+1);s3=digits(n^3);t3=digits((n+1)^3);if(#vecsort(concat(s,s3),,8)==#vecsort(s,,8)+#vecsort(s3,,8)&&#vecsort(concat(t,t3),,8)==#vecsort(t,,8)+#vecsort(t3,,8),print1(n,", ")))
  • Python
    for n in range(10**6):
      s, t = str(n), str(n+1)
      s3, t3 = str(n**3), str((n+1)**3)
      c = 0
      for i in s:
        if s3.count(i):
          c += 1
          break
      for j in t:
        if t3.count(j):
          c += 1
          break
      if not c:
        print(n, end=', ')
    

Extensions

Definition corrected by Robert Israel, Mar 10 2025
Showing 1-8 of 8 results.