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.

A043537 Number of distinct base-10 digits of n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2
Offset: 1

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Author

Keywords

Comments

a(A000079(A130694(n))) = 10. - Reinhard Zumkeller, Jul 29 2007
a(A000290(A016070(n))) = 2. - Reinhard Zumkeller, Aug 05 2010
a(n) = 10 for almost all n. - Charles R Greathouse IV, Oct 02 2013

Crossrefs

Programs

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

A189056 Numbers having in decimal representation at least one common digit with their squares.

Original entry on oeis.org

0, 1, 5, 6, 10, 11, 12, 13, 14, 15, 16, 19, 20, 21, 23, 25, 26, 27, 28, 30, 31, 32, 35, 36, 37, 40, 41, 42, 43, 45, 46, 48, 49, 50, 51, 52, 55, 56, 60, 61, 63, 64, 65, 66, 68, 69, 70, 71, 73, 74, 75, 76, 78, 80, 81, 82, 83, 85, 86, 87, 89, 90, 91, 93, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120
Offset: 1

Views

Author

Reinhard Zumkeller, Apr 16 2011

Keywords

Comments

Complement of A029783; A076493(a(n)) > 0.
A258682(a(n)) < a(n)^2. - Reinhard Zumkeller, Jun 07 2015

Crossrefs

Programs

  • Haskell
    a189056 n = a189056_list !! (n-1)
    a189056_list = 0 : filter (\x -> a258682 x /= x ^ 2) [1..]
    -- Reinhard Zumkeller, Jun 07 2015, Apr 16 2011
    
  • Mathematica
    Select[Range[0,120],Length[Intersection[IntegerDigits[#], IntegerDigits[ #^2]]]>0&] (* Harvey P. Dale, Aug 28 2012 *)
  • PARI
    isok(n) = (n==0) || #setintersect(Set(digits(n)), Set(digits(n^2))); \\ Michel Marcus, Jun 13 2015

A109072 Number of decimal digits ( counted with multiplicity ) in n but not in n^2.

Original entry on oeis.org

0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 2, 0, 1, 0, 1, 2, 1, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 0, 1, 1, 2, 2, 0, 1, 2, 2, 2, 0, 1, 2, 0, 0, 1, 0, 2, 1, 1, 1, 1, 2, 1, 0, 1, 0, 2, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 0, 0, 1, 1, 0, 0, 0, 1, 1, 1
Offset: 0

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Author

Zak Seidov, Jun 20 2005

Keywords

Crossrefs

Cf. A076493 (number of common and distinct decimal digits of n and n^2).
Cf. A109071 (number of common decimal digits (counted with multiplicity) of n and n^2).

Programs

  • Maple
    f:= proc(n) local L2;
    L2:= convert(n^2,base,10);
    nops(remove(t -> member(t,L2), convert(n,base,10)));
    end proc:
    map(f, [$0..200]); # Robert Israel, Feb 22 2017
  • Mathematica
    UnsortedComplement[x_List, y__List]:=Replace[x, Dispatch[(#\[RuleDelayed]Sequence[])&/@Union[y]], 1]; Table[Length[UnsortedComplement[IntegerDigits[n], IntegerDigits[n^2]]], {n, 0, 200}]

A076494 Number of common decimal digits of 2^n and 2^(1+n).

Original entry on oeis.org

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

Views

Author

Labos Elemer, Oct 21 2002

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Length[Intersection[IntegerDigits[2^n], IntegerDigits[2^(n+1)]]], {n, 1, 100}]

A087773 Number of common decimal digits of n and 2^n.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 1, 2, 0, 1, 2, 1, 0, 1, 2, 0, 1, 1, 2, 1, 2, 2, 2, 2, 2, 1, 1, 1, 2, 2, 2, 1, 2, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 0, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 3, 3, 3
Offset: 0

Views

Author

Reinhard Zumkeller, Oct 03 2003

Keywords

Crossrefs

Extensions

More terms from Ray Chandler, Oct 05 2003

A109073 Number of decimal digits ( counted with multiplicity ) in n^2 but not in n.

Original entry on oeis.org

0, 0, 1, 1, 2, 1, 1, 2, 2, 2, 0, 1, 2, 2, 2, 2, 2, 3, 3, 2, 1, 2, 3, 2, 3, 1, 1, 1, 2, 3, 1, 2, 3, 4, 4, 3, 3, 3, 4, 4, 2, 2, 3, 3, 4, 3, 3, 4, 3, 3, 1, 3, 3, 4, 4, 3, 3, 4, 4, 4, 1, 3, 4, 2, 2, 3, 3, 4, 3, 3, 2, 3, 4, 3, 2, 2, 1, 4, 3, 4, 2, 3, 3, 2, 4, 3, 3, 3, 4, 3, 2, 3, 4, 3, 4, 2, 2, 2, 3, 3, 0, 1, 2, 2, 2
Offset: 0

Views

Author

Zak Seidov, Jun 20 2005

Keywords

Comments

Cf. A076493 Number of common and distinct decimal digits of n and n^2, A109071 Number of common decimal digits ( counted with multiplicity ) of n and n^2, A109072 Number of decimal digits ( counted with multiplicity ) in n but not in n^2.

Examples

			a(35)=4 because 34^2=1156 and there are 4 digits (counted with multiplicity) which are in 34^2 but not in 34.
		

Crossrefs

Programs

  • Mathematica
    UnsortedComplement[x_List, y__List]:=Replace[x, Dispatch[(#\[RuleDelayed]Sequence[])&/@Union[y]], 1]; Table[Length[UnsortedComplement[IntegerDigits[n], IntegerDigits[n^2]]], {n, 0, 200}]
Showing 1-7 of 7 results.