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 11 results. Next

A154532 a(n) is the largest 10-digit number whose n-th power contains each digit (0-9) n times, or -1 no such number exists.

Original entry on oeis.org

9876543210, 9994363488, 9999257781, 9999112926, 9995722269, 9999409158, 9998033316, 9993870774, 9986053188, 9964052493, 9975246786, 9966918135, 9938689137, 9998781633, 9813743148, 9970902252, 9740383767, 9829440591, 9873773268, 9985819785, 9766102146, 9863817738
Offset: 1

Views

Author

Zhining Yang, Jan 11 2009

Keywords

Comments

A number with 10*n digits may have all ten digits (0-9) repeated n times. The probability of this is (10n)!/((n!)^10 * 10^((10*n)-10^(10*n-1)). There are 10^10-10^(10-1/n)) numbers which are n-th powers of 10-digit numbers. So there may exist Count=(10n)!*(10^10-10^(10-1/n)))/((n!)^10 * 10^((10*n)-10^(2*n-1)) numbers with the desired property.
From a(23) to a(110) the only terms which exist are a(24)=9793730157, a(26)=9347769564, a(35)=9959167017, and a(38)=9501874278. (The other values of a(n) are -1.) - Zhining Yang, Oct 05 2022

Examples

			a(18) = 9829440591, so each digit (0-9) appears 18 times in the decimal expansion of 9829440591^18.
		

Crossrefs

Programs

  • Python
    def flag(p, n):
        b = True
        for i in range(10):
            if not p.count(str(i)) == n:
                b = False
                break
        return b
    def a(n):
        for i in range(10 ** 10 - 1, 3 * int(10 ** (10 - 1 / n) / 3), -3):
            p = str(i ** n)
            if flag(p, n) == True:
                return i
                break
    for i in range(1, 23):
        print(i, a(i))  # Zhining Yang, Oct 10 2022
    
  • Python
    def flag(p, n):
        return all(p.count(d) == n for d in "0123456789")
    def a(n):
        return next(i for i in range(10**10-1,3*int(10**(10-1/n)/3), -3) if flag(str(i**n), n))
    for i in range(2, 23):
        print(i,a(i))  # Michael_S._Branicky, Oct 10 2022

Extensions

Edited by N. J. A. Sloane, Jan 12 2009
a(19)-a(22) from Zhining Yang, Oct 05 2022
Definition revised by N. J. A. Sloane, Nov 22 2022

A154871 Numbers n such that n^6 contains every digit exactly 4 times.

Original entry on oeis.org

3470187, 3554463, 3887058, 4328241, 4497738
Offset: 1

Views

Author

Zhining Yang, Jan 16 2009

Keywords

Comments

a(1) is also the number of A074205

Examples

			3887058^6=3449261536602702380309782557611971988544, which contains 4 times of each digit 0-9. Total 5 terms
		

Crossrefs

A154873 Numbers n such that n^5 contains every digit exactly 3 times.

Original entry on oeis.org

643905, 680061, 720558, 775113, 840501, 878613, 984927
Offset: 1

Views

Author

Zhining Yang, Jan 16 2009

Keywords

Comments

a(5) is also the number of A074205

Examples

			840501^5=419460598737334268928156702501, which contains exactly 3 times of each digit 0-9. Total 7 terms
		

Crossrefs

Programs

  • Mathematica
    Select[Range[630972,999978],Union[DigitCount[#^5]]=={3}&] (* Harvey P. Dale, May 01 2021 *)

A154874 Numbers k such that k^3 contains every digit exactly twice.

Original entry on oeis.org

2158479, 2190762, 2205528, 2219322, 2301615, 2330397, 2336268, 2345811, 2358828, 2359026, 2367609, 2388534, 2389119, 2389638, 2397132, 2428986, 2504736, 2524974, 2536152, 2583258, 2590125, 2607222, 2620827, 2622012, 2647866, 2649369, 2658636, 2671593
Offset: 1

Views

Author

Zhining Yang, Jan 16 2009

Keywords

Comments

This sequence has 138 terms.

Examples

			2358828^3 = 13124683009764879552, which contains each digit 0..9 exactly twice.
		

Crossrefs

Programs

  • Maple
    lim:=floor((10^20)^(1/3)): for j from ceil((10^19)^(1/3)) to lim do d:=convert(j^3,base,10): doubdig:=true: for k from 0 to 9 do if(numboccur(d,k)<>2)then doubdig:=false:break: fi: od: if(doubdig)then print(j); fi: od: # Nathaniel Johnston, May 28 2011
  • Mathematica
    With[{cmin=Ceiling[Surd[10^19,3]],cmax=Floor[Surd[10^20,3]]},Select[ Range[ cmin, cmax], Union[ DigitCount[#^3]]=={2}&]] (* Harvey P. Dale, Nov 17 2018 *)

A154818 Numbers k such that k^4 contains every digit exactly twice.

Original entry on oeis.org

69636, 70215, 77058, 80892
Offset: 1

Views

Author

Zhining Yang, Jan 15 2009

Keywords

Comments

77058^4 = 35259076387041812496, which contains 2 of each digit 0-9. There are just 4 terms.

Crossrefs

Extensions

Keywords fini and full added. - R. J. Mathar, Jan 17 2009

A357755 Number of solutions for a 10-digit number whose n-th power contains each digit (0-9) exactly n times.

Original entry on oeis.org

3265920, 468372, 65663, 15487, 5020, 1930, 855, 417, 246, 114, 97, 45, 33, 24, 20, 18, 7, 6, 1, 3, 2, 3, 0, 1, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1
Offset: 1

Views

Author

Zhining Yang, Nov 26 2022

Keywords

Comments

A number with 10*n digits may have all ten digits (0-9) repeated n times. The probability of this is (10*n)!/((n!)^10 * (10^(10*n)-10^(10*n-1))). There are 10^10-10^(10-1/n) numbers which are n-th powers of 10-digit numbers. So there may exist Count = (10*n)!*(10^10-10^(10-1/n))/((n!)^10 * (10^(10*n)-10^(10*n-1))) numbers with the desired property.
No solutions were found for n = 39 to 1000.

Examples

			a(20) = 3 because there are 3 10-digit numbers (8951993472, 9921107394, and 9985819785) whose 20th power contains each digit (0-9) 20 times.
		

Crossrefs

Programs

  • Python
    def flag(p, n):
        return all(p.count(d) == n for d in "0123456789")
    def a(n):
        num=0
        for i in range(10**10-1, 3*int(10**(10-1/n)/3), -3):
            if flag(str(i**n), n):
                num+=1
        return(num)

A154875 Numbers k such that k^4 contains every digit exactly 3 times.

Original entry on oeis.org

17824719, 17940018, 18027474, 18197931, 18326025, 18798396, 18915888, 18929424, 19027455, 19149462, 19180275, 19196064, 19235673, 19311297, 19322913, 19324275, 19328322, 19455918, 19522575, 19757886, 19793664
Offset: 1

Views

Author

Zhining Yang, Jan 16 2009

Keywords

Examples

			22807116 ^ 4 = 270571148920443982076865351936, which contains exactly 3 times of each digit 0-9.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[17824000,31608000],Union[Tally[IntegerDigits[#^4]][[All,2]]]=={3}&] (* Harvey P. Dale, Dec 24 2016 *)
  • PARI
    is(n) = my(v=vector(10), d=digits(n^4)); if(#d!=30,return(0)); for(i=1, #d, v[d[i]+1]++; if(v[d[i]+1] > 3, return(0))); 1 \\ David A. Corneth, Aug 19 2025

A217535 Least number having in its decimal representation each digit n times.

Original entry on oeis.org

1023456789, 10012233445566778899, 100011222333444555666777888999, 1000011122223333444455556666777788889999, 10000011112222233333444445555566666777778888899999, 100000011111222222333333444444555555666666777777888888999999
Offset: 1

Views

Author

M. F. Hasler, Oct 05 2012

Keywords

Crossrefs

Programs

  • Maple
    a:= n-> parse(cat(1,0$n,1$(n-1),seq(i$n, i=2..9))):
    seq(a(n), n=1..10);  # Alois P. Heinz, Jun 25 2017
  • PARI
    A217535(n)=sum(d=1,9,10^(n-(d==1))\9*d*10^(n*(9-d)))+10^(10*n-1)

Formula

a(n) ~ 10^(10n-1). See PARI code for an exact formula.

A370667 Largest pandigital number whose n-th power contains each digit (0-9) exactly n times.

Original entry on oeis.org

9876543210, 9876124053, 9863527104, 9846032571, 9847103256, 9247560381
Offset: 1

Views

Author

Zhining Yang, Mar 13 2024

Keywords

Comments

If an n-th power of a pandigital number k contains each digit (0-9) exactly n times, it implies that 10^(10 - 1/n) <= 9876543210, so n <= 185. It's easy to verify that no solutions exist for n=7 to 185.

Examples

			a(4) = 9846032571 because it is the largest 10-digit number that contains each digit (0-9) exactly once and its 4th power 9398208429603554221689707364750715341681 contains each digit (0-9) exactly 4 times.
		

Crossrefs

Programs

  • Mathematica
    s=FromDigits/@Permutations[Range[0,9]];For[n=1,n<=6,n++,For[k=Length@s,k>0,k--,If[Count[Tally[IntegerDigits[s[[k]]^n]][[All,2]],n]==10,Print[{n,s[[k]]}];Break[]]]]
  • Python
    from itertools import permutations
    a=[]
    for n in range(1,7):
        for k in [int(''.join(d)) for d in permutations('9876543210', 10)]:
            if all(str(k**n).count(d) ==n for d in '0123456789'):
                a.append(k)
                break
    print(a)

A154876 10-digit numbers n such that n^16 contains every digit exactly 16 times.

Original entry on oeis.org

8691229761, 8776040742, 8800099059, 8812428855, 8813522223, 8815323864, 8823675177, 8886940968, 9239038038, 9324907263, 9480130515, 9500938647, 9643844169, 9801034758, 9857840688, 9872688021, 9962545842, 9970902252
Offset: 1

Views

Author

Zhining Yang, Jan 16 2009

Keywords

Comments

The search program was provided by wuxinren(http://bbs.emath.ac.cn/space-uid-80.html): http://bbs.emath.ac.cn/attachment.php?aid=697&k=37ef434325a887e1a6f268d69d06192a&t=1232126232

Examples

			8691229761^16=1059984945135973085116625441940958734567890938937942910046410302827750560860737374626331724228885721853160790705924439371252226476405367618058329962361885148161 means that 16th power of 8691229761 has all digit(0-9) each for 16 times exactly
		

Crossrefs

Showing 1-10 of 11 results. Next