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 10 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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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

A029785 Numbers k whose cube k^3 has no digit in common with k.

Original entry on oeis.org

2, 3, 7, 8, 22, 27, 43, 47, 48, 52, 53, 63, 68, 77, 92, 157, 172, 177, 187, 188, 192, 222, 223, 252, 263, 303, 378, 408, 423, 442, 458, 468, 477, 478, 487, 527, 552, 558, 577, 587, 588, 608, 648, 692, 707, 772, 808, 818, 823, 843, 888, 918, 922
Offset: 1

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Comments

Original name: Digits of n are not present in n^3.
Might be called "Exclusionary Cubes", although this might be reserved for terms having no duplicate digits, cf. link to rec.puzzles discussion group. In that case the largest term would be 7658 = A113951(3). - M. F. Hasler, Oct 17 2018; corrected thanks to David Radcliffe and Michel Marcus, Apr 30 2020

Examples

			k = 80800000008880080808880080088 is in the sequence because the 87-digit number k^3 has only digits 1, ..., 7 and 9. - _M. F. Hasler_, Oct 16 2018
		

Crossrefs

Programs

  • Mathematica
    Select[Range[5000], Intersection[IntegerDigits[#], IntegerDigits[#^3]]=={}&] (* Vincenzo Librandi, Oct 04 2013 *)
  • PARI
    is(n)=my(d=Set(digits(n))); setminus(d,Set(digits(n^3)))==d \\ Charles R Greathouse IV, Oct 02 2013
    
  • PARI
    is_A029785(n)=setintersect(Set(digits(n)),Set(digits(n^3)))==[] \\ M. F. Hasler, Oct 16 2018

Extensions

Name reworded by Jon E. Schoenfield and M. F. Hasler, Oct 16 2018

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

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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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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

A253574 Primes p such that digits of p do not appear in p^4.

Original entry on oeis.org

2, 3, 7, 53, 59, 67, 89, 383, 887, 2027, 3253, 5669, 7993, 8009, 9059, 53633, 54667, 56533, 88883, 272777777, 299222299, 383833883, 797769997
Offset: 1

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Author

Vincenzo Librandi, Jan 04 2015

Keywords

Comments

Primes in A111116.
No further terms up to 10^9. - Felix Fröhlich, Jan 04 2015
No further terms up to 10^10. - Chai Wah Wu, Jan 06 2015
No further terms up to 2.5*10^13 - Giovanni Resta, Jun 01 2015
No further terms up to 10^19 (via A111116). - Michael S. Branicky, Jan 05 2022

Examples

			2 and 2^4=16 have no digits in common, hence 2 is in the sequence.
		

Crossrefs

Cf. A111116.
Cf. primes such that digits of p do not appear in p^k: A030086 (k=2), A030087 (k=3), this sequence (k=4), no terms (k=5), A253575 (k=6), A253576 (k=7), A253577 (k=8), no terms (k=9), A253578 (k=10).

Programs

  • Mathematica
    Select[Prime[Range[1000000]], Intersection[IntegerDigits[#], IntegerDigits[#^4]]=={} &]
  • PARI
    forprime(p=1, 1e9, dip=digits(p); dipf=digits(p^4); sharedi=0; for(i=1, #dip, for(j=1, #dipf, if(dip[i]==dipf[j], sharedi++; break({2})))); if(sharedi==0, print1(p, ", "))) \\ Felix Fröhlich, Jan 04 2015
    
  • Python
    from sympy import isprime
    A253574_list = [n for n in range(1,10**6) if set(str(n)) & set(str(n**4)) == set() and isprime(n)]
    # Chai Wah Wu, Jan 06 2015

Extensions

a(20)-a(23) from Felix Fröhlich, Jan 04 2015

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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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

A113951 Largest number whose n-th power is exclusionary (or 0 if no such number exists).

Original entry on oeis.org

639172, 7658, 2673, 0, 92, 93, 712, 0, 18, 12, 4, 0, 37, 0, 9, 0, 0, 3, 4, 0, 7, 2, 7, 0, 8, 3, 9, 0, 0, 0, 0, 0, 3, 2, 2, 0, 0, 7, 3, 0, 2, 0, 0, 0, 2, 0, 0, 0, 3, 0, 0, 0, 2, 3, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3
Offset: 2

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Author

Lekraj Beedassy, Nov 09 2005

Keywords

Comments

The number m with no repeated digits has an exclusionary n-th power m^n if the latter is made up of digits not appearing in m. For the corresponding m^n see A113952. In principle, no exclusionary n-th power exists for n == 1 (mod 4) = A016813.
After a(84) = 3, the next nonzero term is a(168) = 2, where 168 is the last known term in A034293. - Michael S. Branicky, Aug 28 2021

Examples

			a(4) = 2673 because no number with distinct digits beyond 2673 has a 4th power that shares no digit in common with it (see A111116). Here we have 2673^4 = 51050010415041.
		

References

  • H. Ibstedt, Solution to Problem 2623, "Exclusionary Powers", pp. 346-9 Journal of Recreational Mathematics, Vol. 32 No.4 2003-4, Baywood NY.

Crossrefs

Programs

  • Python
    from itertools import combinations, 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 a(n):
        m = 0
        for k in no_repeated_digits():
            if set(str(k)) & set(str(k**n)) == set():
                m = max(m, k)
        return m
    for n in range(2, 4): print(a(n), end=", ") # Michael S. Branicky, Aug 28 2021

Extensions

a(34), a(39), a(40) corrected by and a(43) and beyond from Michael S. Branicky, Aug 28 2021

A113318 Numbers whose biquadrates (fourth powers) are exclusionary.

Original entry on oeis.org

2, 3, 4, 7, 8, 9, 24, 27, 28, 32, 42, 52, 53, 58, 59, 67, 89, 93, 203, 258, 284, 324, 329, 832, 843, 2673
Offset: 1

Views

Author

Lekraj Beedassy, Oct 26 2005

Keywords

Comments

The number m with no repeated digits has an exclusionary fourth power m^4 if the latter is made up of digits not appearing in m. Is a subsequence of A111116. Conjectured to be complete. For the corresponding exclusionary biquadrates m^4, see A113317.

References

  • H. Ibstedt, Solution to Problem 2623, "Exclusionary Powers", pp. 346-9, Journal of Recreational Mathematics, Vol. 32 No.4 2003-4 Baywood NY.

Programs

  • Mathematica
    ebQ[n_]:=Max[DigitCount[n]]==1&&Intersection[IntegerDigits[n], IntegerDigits[ n^4]]=={}; Select[Range[3000],ebQ] (* Harvey P. Dale, Aug 21 2013 *)

A253606 Numbers n such that digits of n are not present in n^8.

Original entry on oeis.org

3, 4, 8, 9, 22, 33, 43, 54, 59, 73, 222, 233, 353, 712, 777, 22224
Offset: 1

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Author

Chai Wah Wu, Jan 05 2015

Keywords

Comments

a(17) > 10^9.

Examples

			4^8 = 65536 which does not contain the digit 4.
		

Crossrefs

Programs

  • Mathematica
    a253606[n_] := Block[{f},
      f[x_] := MemberQ[IntegerDigits[x^8], #] & /@ IntegerDigits[x];
    Select[Range@n, DeleteDuplicates@f[#] == {False} &]]; a253606[10^5] (* Michael De Vlieger, Jan 06 2015 *)
  • Python
    A253606_list = [n for n in range(1,10**6) if set(str(n)) & set(str(n**8)) == set()]

A254130 Numbers whose factorials are exclusionary: numbers n such that n and n! have no digits in common.

Original entry on oeis.org

0, 3, 5, 6, 7, 8, 9, 13, 16
Offset: 1

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Author

Felix Fröhlich, May 03 2015

Keywords

Comments

Conjecture: The sequence is finite, with 16 being the last term.
If A182049 is finite, then this sequence is finite. If 41 is the largest term in A182049 (as is conjectured), then 16 is the largest term of this sequence. - M. F. Hasler, May 04 2015

Examples

			13! = 6227020800. 13 and 6227020800 have no digits in common, so 13 is a term of the sequence.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[0,16],DisjointQ[IntegerDigits[#],IntegerDigits[#!]]&] (* Ivan N. Ianakiev, May 04 2015 *)
  • PARI
    is(n)=#setintersect(Set(digits(n)), Set(digits(n!)))==0
Showing 1-10 of 10 results.