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.

Previous Showing 11-16 of 16 results.

A052421 Numbers without 8 as a digit.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 34, 35, 36, 37, 39, 40, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 59, 60, 61, 62, 63, 64, 65, 66, 67, 69, 70, 71, 72, 73, 74, 75, 76, 77, 79
Offset: 1

Views

Author

Henry Bottomley, Mar 13 2000

Keywords

Crossrefs

Cf. A004183, A004727, A038616 (subset of primes), A082837 (Kempner series).
Cf. A052382 (without 0), A052383 (without 1), A052404 (without 2), A052405 (without 3), A052406 (without 4), A052413 (without 5), A052414 (without 6), A052419 (without 7), A007095 (without 9).

Programs

  • Haskell
    a052421 = f . subtract 1 where
    f 0 = 0
    f v = 10 * f w + if r > 7 then r + 1 else r where (w, r) = divMod v 9
    -- Reinhard Zumkeller, Oct 07 2014
    
  • Magma
    [ n: n in [0..89] | not 8 in Intseq(n) ]; // Bruno Berselli, May 28 2011
    
  • Maple
    a:= proc(n) local l, m; l, m:= 0, n-1;
          while m>0 do l:= (d->
            `if`(d<8, d, d+1))(irem(m, 9, 'm')), l
          od; parse(cat(l))/10
        end:
    seq(a(n), n=1..100);  # Alois P. Heinz, Aug 01 2016
  • Mathematica
    Select[Range[0,100],DigitCount[#,10,8]==0&] (* Harvey P. Dale, Oct 11 2012 *)
  • PARI
    lista(nn)=for (n=0, nn, if (!vecsearch(vecsort(digits(n),,8), 8), print1(n, ", "));); \\ Michel Marcus, Feb 22 2015
    
  • PARI
    /* See OEIS wiki page (cf. LINKS) for more programs. */
    apply( {A052421(n)=fromdigits(apply(d->d+(d>7),digits(n-1,9)))}, [1..99]) \\ a(n)
    select( {is_A052421(n)=!setsearch(Set(digits(n)),8)}, [0..99]) \\ used in A038616
    next_A052421(n, d=digits(n+=1))={for(i=1,#d, d[i]==8&&return((1+n\d=10^(#d-i))*d)); n} \\ Least a(k) > n. Used in A038616. - M. F. Hasler, Jan 11 2020
    
  • Python
    from gmpy2 import digits
    def A052421(n): return int(digits(n-1,9).replace('8','9')) # Chai Wah Wu, Jun 28 2025
  • sh
    seq 0 1000 | grep -v 8; # Joerg Arndt, May 29 2011
    

Formula

a(n) = replace digits d > 7 by d + 1 in base-9 representation of n - 1. - Reinhard Zumkeller, Oct 07 2014
Sum_{n>1} 1/a(n) = A082837 = 22.726365... (Kempner series). - Bernard Schott, Jan 12 2020, edited by M. F. Hasler, Jan 13 2020

Extensions

Offset changed by Reinhard Zumkeller, Oct 07 2014

A082832 Decimal expansion of Sum_{k >= 1, k has no digit 3 in base 10} 1/k.

Original entry on oeis.org

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

Views

Author

Robert G. Wilson v, Apr 14 2003

Keywords

Comments

Numbers with a digit 3 (A011533) have asymptotic density 1, i.e., almost all terms are removed from the harmonic series, which makes convergence less surprising. See A082839 (the analog for digit 0) for more information about such so-called Kempner series. - M. F. Hasler, Jan 13 2020

Examples

			20.569877950961230371075217419053111414153869674730783489508528500... - _Robert G. Wilson v_, Jun 01 2009
		

References

  • Julian Havil, Gamma, Exploring Euler's Constant, Princeton University Press, Princeton and Oxford, 2003, page 34.

Crossrefs

Cf. A002387, A024101, A052405 (numbers with no '3'), A011533 (numbers with '3').
Cf. A082830, A082831, A082833, A082834, A082835, A082836, A082837, A082838, A082839 (analog for digits 1, 2, 4, ..., 9 and 0).

Programs

  • Mathematica
    (* see the Mmca in Wolfram Library Archive. - Robert G. Wilson v, Jun 01 2009 *)

Formula

Equals Sum_{k in A052405\{0}} 1/k, where A052405 = numbers with no digit 3. - M. F. Hasler, Jan 15 2020

Extensions

More terms from Robert G. Wilson v, Jun 01 2009

A235498 For k in {2,3,...,9} define a sequence as follows: a(0)=0; for n>=0, a(n+1)=a(n)+1, unless a(n) ends in k, in which case a(n+1) is obtained by replacing the last digit of a(n) with the digit(s) of k^2. This is k(2).

Original entry on oeis.org

0, 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 31, 32, 34, 35, 36, 37, 38, 39, 40, 41, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 71, 72, 74
Offset: 0

Views

Author

Vincenzo Librandi, Feb 06 2014

Keywords

Comments

An alternative and simpler definition: numbers not ending in 3. - Charles R Greathouse IV, Feb 07 2014

Crossrefs

Subsequence of A052405.

Formula

G.f.: (x^9 +x^8 +x^7 +x^6 +x^5 +x^4 +2*x^3 +x^2 +x) / (x^10 -x^9 -x +1). - Alois P. Heinz, Feb 07 2014

Extensions

Definition by N. J. A. Sloane, Feb 07 2014

A004178 Omit 3's from n.

Original entry on oeis.org

0, 1, 2, 0, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 14, 15, 16, 17, 18, 19, 20, 21, 22, 2, 24, 25, 26, 27, 28, 29, 0, 1, 2, 0, 4, 5, 6, 7, 8, 9, 40, 41, 42, 4, 44, 45, 46, 47, 48, 49, 50, 51, 52, 5, 54, 55, 56, 57, 58, 59, 60, 61, 62, 6, 64, 65, 66, 67, 68, 69, 70, 71, 72, 7, 74
Offset: 0

Views

Author

Keywords

Comments

a(n) = 0 when n = 0 or when n is a 3-repdigit (A002277). a(n) = n when it contains no 3 among its digits. - Alonso del Arte, Oct 16 2012

Examples

			a(13) = 1 because after deleting the 3 from its base 10 representation, we're left with 1.
a(14) = 14 because there are no 3s to delete.
		

Crossrefs

Programs

  • Mathematica
    Table[FromDigits[DeleteCases[IntegerDigits[n], 3]], {n, 0, 74}] (* Alonso del Arte, Oct 16 2012 *)
  • PARI
    a(n)=subst(Pol(select(k->k-3,digits(n))),'x,10) \\ Charles R Greathouse IV, Oct 16 2012

A244008 Nonnegative integers with no repeated letters in their combined English decimal digit names.

Original entry on oeis.org

0, 1, 2, 4, 5, 6, 8, 16, 25, 26, 46, 48, 52, 60, 61, 62, 64, 84
Offset: 1

Views

Author

Rick L. Shepherd, Jun 17 2014

Keywords

Examples

			The first multi-digit term is 16 since "one" and "six" taken together contain no duplicate letters. Although "one" itself contains no duplicate letters, by definition 11 is not a term since duplicate digits introduce repeated letters.
		

Crossrefs

Subsequence of A010784, A052405, A052419, and A007095.
Cf. A059916.

Programs

  • PARI
    is(n)=my(d=apply(k->[25,9,40,64,26,7,4,64,37,64][k+1], digits(n)),t); for(i=1,#d, if(bitand(t,d[i]), return(0)); t=bitor(t,d[i])); t<64 \\ Charles R Greathouse IV, Aug 18 2022
  • Python
    m = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"]
    def nr(w): return len(w) == len(set(w))
    afull = [k for k in range(988) if nr("".join(m[int(d)] for d in str(k)))]
    print(afull) # Michael S. Branicky, Aug 18 2022
    

A338287 Decimal expansion of the sum of reciprocals of the numbers that are not pandigital numbers (version 2, A171102).

Original entry on oeis.org

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

Views

Author

Amiram Eldar, Oct 20 2020

Keywords

Comments

The sum of the reciprocals of the terms of the complement of A171102: numbers with at most 9 distinct digits. It is the union of the 10 sequences of numbers without a single given digit (see the Crossrefs section).
The terms in the data section were taken from the 200 decimal digits given by Strich and Müller (2020).

Examples

			65.74331110185328196734583167680868411685344106635398...
		

Crossrefs

Cf. A052382 (numbers without the digit 0), A052383 (without 1), A052404 (without 2), A052405 (without 3), A052406 (without 4), A052413 (without 5), A052414 (without 6), A052419 (without 7), A052421 (without 8), A007095 (without 9).

Formula

Equals 1/1 + 1/2 + 1/3 + ... + 1/1023456788 + 1/1023456790 + ..., i.e., A171102(1) = 1023456789 is the first number whose reciprocal is not in the sum.
Previous Showing 11-16 of 16 results.