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 1-7 of 7 results.

A033023 Numbers whose base-10 expansion has no run of digits with length < 2.

Original entry on oeis.org

11, 22, 33, 44, 55, 66, 77, 88, 99, 111, 222, 333, 444, 555, 666, 777, 888, 999, 1100, 1111, 1122, 1133, 1144, 1155, 1166, 1177, 1188, 1199, 2200, 2211, 2222, 2233, 2244, 2255, 2266, 2277, 2288, 2299, 3300, 3311, 3322, 3333
Offset: 1

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Author

Keywords

Comments

Contains A014181 as subsequence. A115853 is a supersequence. - M. F. Hasler, Jun 24 2016

Crossrefs

Programs

  • Mathematica
    Select[Range[10000], Min[Length/@Split[IntegerDigits[#, 10]]]>1&] (* Vincenzo Librandi, Feb 05 2014 *)
  • PARI
    is(n)={n=digits(n);while(#n>2 && n[2]==n[1], n=if(n[3]==n[1],n[^1],n[3..-1]));#n>1&&n[1]==n[2]} \\ M. F. Hasler, Jun 24 2016

A115853 Numbers where every digit that is present occurs more than once (not necessarily consecutively).

Original entry on oeis.org

11, 22, 33, 44, 55, 66, 77, 88, 99, 111, 222, 333, 444, 555, 666, 777, 888, 999, 1001, 1010, 1100, 1111, 1122, 1133, 1144, 1155, 1166, 1177, 1188, 1199, 1212, 1221, 1313, 1331, 1414, 1441, 1515, 1551, 1616, 1661, 1717, 1771, 1818, 1881, 1919, 1991, 2002
Offset: 1

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Author

Keywords

Comments

Through terms shown, this is also numbers where every digit present occurs the same number of times (not necessarily consecutively). The first number in this sequence not in that one is 10001.

Crossrefs

Programs

  • Maple
    filter:= proc(n)
    local L,S;
    L:= convert(n,base,10);
    S:= convert(L,set);
    min(seq(numboccur(i,L),i=S)) > 1
    end proc:
    select(filter, [$1..10000]); # Robert Israel, May 28 2014
  • Mathematica
    edQ[n_]:=Min[Select[DigitCount[n],#!=0&]]>1; Select[Range[2100],edQ] (* Harvey P. Dale, Dec 13 2018 *)

A179309 The smallest number that has more copies of some digit than any previous number in the sequence.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 22, 33, 44, 55, 66, 77, 88, 99, 100, 111, 222, 333, 444, 555, 666, 777, 888, 999, 1000, 1111, 2222, 3333, 4444, 5555, 6666, 7777, 8888, 9999, 10000, 11111, 22222, 33333, 44444, 55555, 66666, 77777, 88888, 99999, 100000
Offset: 1

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Author

Jack W Grahl, Jul 10 2010

Keywords

Comments

These are, for each digit d and each natural number k, the smallest positive number in which the digit d appears k (or more) times, in numerical order. They are all numbers with all digits repeated except numbers of the form 10^m.
If we started with 0 the term 10 would be missed and all other terms would be the same.

Examples

			100 is included because no previous term contains two 0's. 111 is included because no previous term contains more than 2 1's. Every number between 101 and 110 inclusive is omitted because each contains at most 2 1's (no more than 11) and at most 1 of any other digit (no more than 2 thru 10).
		

Crossrefs

Supersequence of A014181 and A010785. See also A179310.

Programs

  • Mathematica
    With[{nn=5},Join[Flatten[Table[FromDigits[PadRight[{},i,n]],{i,nn},{n,9}]],10^Range[nn]]]//Sort (* Harvey P. Dale, May 31 2016 *)

A288068 Repdigits in base 10 which are Brazilian numbers.

Original entry on oeis.org

7, 8, 22, 33, 44, 55, 66, 77, 88, 99, 111, 222, 333, 444, 555, 666, 777, 888, 999, 1111, 2222, 3333, 4444, 5555, 6666, 7777, 8888, 9999, 11111, 22222, 33333, 44444, 55555, 66666, 77777, 88888, 99999, 111111, 222222, 333333, 444444, 555555, 666666, 777777, 888888, 999999
Offset: 1

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Author

Bernard Schott, Jun 05 2017

Keywords

Comments

These numbers are all repdigits belonging to A010785. The representation of the numbers 7 and 8 in base 10 is not Brazilian but they are yet Brazilian because 7 = 111_2 and 8 = 22_3. Except the repdigits 7, 8, 22, 33, 55, 77 and the primes repunits R_n from A004022 and A004023, all these Brazilian repdigits are also Brazilian in another base.
Contains all base-10 repdigits (A010785) >= 22, because these are Brazilian numbers in base 10. - R. J. Mathar, Jul 19 2024

Examples

			7 = 111_2;
44 = 44_10 = 22_21;
66 = 66_10 = 33_21 = 22_32.
		

Crossrefs

Programs

  • Maple
    # reuses code of A125134, b-file output
    n := 1 :
    for ndigs from 1 do
        for d from 1 to 9 do
            r := add(d*10^i,i=0..ndigs-1) ; # rep digit d in base 10
            if isA125134(r) then
                printf("%d %d\n",n,r) ;
                n := n+1 ;
            end if;
        end do:
    end do: # R. J. Mathar, Jul 19 2024
  • Mathematica
    Select[Flatten@ Table[FromDigits@ ConstantArray[k, n], {n, 6}, {k, 9}], Function[n, Length@ SelectFirst[Range[2, n - 2], Count[DigitCount[n, #], ?(# > 0 &)] == 1 &] == 0]] (* _Michael De Vlieger, Jun 06 2017, Version 10 *)

A347189 Positive integers that can be expressed as the sum of powers of their digits (from right to left) with consecutive natural exponents.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 24, 332, 1676, 121374, 4975929, 134116265, 1086588775, 3492159897, 8652650287, 8652650482
Offset: 1

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Author

Reiner Moewald, Aug 21 2021

Keywords

Comments

Any number > 9 consisting of just one digit (A014181) can't be in the list. (Provable using the Carmichael function.)

Examples

			24 = 4^2 + 2^3 is a term.
332 = 2^3 + 3^4 + 3^5 is another term.
		

Crossrefs

Programs

  • Python
    liste = []
    for ex in range(0, 20):
        for t in range(1, 10000):
            n = t
            pot = ex
            ergebnis = 0
            while n > 0:
                pot = pot + 1
                rest = n % 10
                n = (n - rest) // 10
                zw = 1
                for i in range(pot):
                    zw = zw * rest
                ergebnis = ergebnis + zw
            if (int(ergebnis) == t) and (t not in liste):
                liste.append(t)
    liste.sort()
    print(liste)
    
  • Python
    def powsum(digits, startexp):
        return sum(digits[i]**(startexp+i) for i in range(len(digits)))
    def ok(n):
        if n < 10: return True
        s = str(n)
        if set(s) <= {'0', '1'}: return False
        digits, startexp = list(map(int, s))[::-1], 1
        while powsum(digits, startexp) < n: startexp += 1
        return n == powsum(digits, startexp)
    print(list(filter(ok, range(2*10**5)))) # Michael S. Branicky, Aug 29 2021

Extensions

a(15)-a(19) from Michael S. Branicky, Aug 31 2021

A084434 Numbers whose digit permutations have GCD > 1.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 15, 18, 20, 21, 22, 24, 26, 27, 28, 30, 33, 36, 39, 40, 42, 44, 45, 46, 48, 50, 51, 54, 55, 57, 60, 62, 63, 64, 66, 68, 69, 70, 72, 75, 77, 78, 80, 81, 82, 84, 86, 87, 88, 90, 93, 96, 99, 102, 105, 108, 111, 114, 117, 120, 123, 126, 129, 132
Offset: 1

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Author

Amarnath Murthy, Jun 02 2003

Keywords

Comments

Numbers k such that there is a number d>1 which divides every number that can be obtained by permuting the digits of k. - N. J. A. Sloane, Aug 27 2020
Theorem. The sequence consists of: (1) A008585 (multiples of 3), (2) A014263 (numbers with all digits even), (3) A014181 (numbers with all digits equal), (4) numbers with all digits 5 or 0, (5) numbers with all digits 7 or 0, (6) numbers with 6k digits, all of which are 1 or 8, and (7) numbers with 6k digits, all of which are 2 or 9. - David Wasserman, May 07 2004

Examples

			72 is in the sequence because 72 and 27 are both divisible by 9.
		

Crossrefs

Subsequence of A084433 which contains for example 592 which is not in here.

Programs

  • Mathematica
    Select[Range[0, 150], GCD @@ FromDigits /@ Permutations[IntegerDigits[#]] > 1 &]  (* Harvey P. Dale, Jan 12 2011 *)

Extensions

More terms from David Wasserman, May 07 2004
Initial zero removed, Harvey P. Dale, Jan 14 2011
Entry revised by N. J. A. Sloane, Aug 27 2020

A166713 Alliterative-digit numbers: Positive integers n such that the English names of the decimal digits of n begin with the same letter; ignore single-digit numbers.

Original entry on oeis.org

11, 22, 23, 32, 33, 44, 45, 54, 55, 66, 67, 76, 77, 88, 99, 111, 222, 223, 232, 233, 322, 323, 332, 333, 444, 445, 454, 455, 544, 545, 554, 555, 666, 667, 676, 677, 766, 767, 776, 777, 888, 999, 1111, 2222, 2223, 2232, 2233, 2322, 2323, 2332, 2333, 3222, 3223
Offset: 1

Views

Author

Rick L. Shepherd, Oct 19 2009

Keywords

Comments

The multi-digit repdigits (A014181) are a subsequence. No term contains the digit 0 (zero). All terms containing digits 1 (one), 8 (eight), or 9 (nine) are also terms of A014181. Any term not mentioned above is a string of 2's (twos) and 3's (threes) only (a multi-digit term of A032810), 4's (fours) and 5's (fives) only, or 6's (sixes) and 7's (sevens) only.

Examples

			454 is a term as digits "four", "five", "four" each begin with the letter "f".
		

Crossrefs

Showing 1-7 of 7 results.