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 1-4 of 4 results.

A171102 Pandigital numbers: numbers containing the digits 0-9. Version 2: each digit appears at least once.

Original entry on oeis.org

1023456789, 1023456798, 1023456879, 1023456897, 1023456978, 1023456987, 1023457689, 1023457698, 1023457869, 1023457896, 1023457968, 1023457986, 1023458679, 1023458697, 1023458769, 1023458796, 1023458967, 1023458976
Offset: 1

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Author

N. J. A. Sloane, Sep 25 2010

Keywords

Comments

This is the infinite version. See A050278 for the finite version.
The first 9*9!=3265920 terms of this sequence are permutations of the digits 0-9 with a(9*9!)=9876543210 (see Version 1, A050278). - Jeremy Gardiner, May 29 2010
Subsequence of A134336 and of A178403; A178401(a(n))>0. - Reinhard Zumkeller, May 27 2010
Smallest prime factors: A178775(n) = A020639(a(n)). - Reinhard Zumkeller, Jun 11 2010
A178788(a(n)) = 1, for n <= 9*9!, else A178788(a(n)) = 0. - Reinhard Zumkeller, Jun 30 2010 [corrected by Hieronymus Fischer, Feb 02 2013]
A230959(a(n)) = 0. - Reinhard Zumkeller, Nov 02 2013
The first term of the sequence absent in A050278 is a(3265921) = 10123456789. Also, the first prime is a(3306373) = 10123457689 = A050288(1). - Zak Seidov, Sep 23 2015
Almost all numbers are in this sequence, in the sense that it has asymptotic density equal to 1. Indeed, the fraction of n-digit numbers which don't have a given digit d is roughly 0.9^n (not exactly because the first digit is chosen among {1..9}) which tends to zero as n -> oo. - M. F. Hasler, Jan 05 2020

Crossrefs

Subsequence of A253172.

Programs

  • Mathematica
    Take[ Select[ FromDigits@# & /@ Permutations[ Range[0, 9], {10}], # > 10^9 &], 20] (* Robert G. Wilson v, May 30 2010 *)
  • PARI
    is_A171102(n)=9<#vecsort(Vecsmall(Str(n)),,8) /* assuming that n is a nonnegative integer. In PARI/GP V.2.4 - 2.9 this is faster than other possibilities involving Set(),Vec(),eval() or digits() */ \\ M. F. Hasler, Jan 10 2012, Sep 19 2017
    
  • PARI
    A171102=A050278 /*** valid for n <= 9*9! ***/ \\ M. F. Hasler, Jan 10 2012

Formula

a(n) = 1011111111 + A178478(n) for n = 1,...,8!. - M. F. Hasler, Jan 10 2012
A171102(n) = A050278(n) for n <= 9*9!.

A050289 Zeroless pandigital numbers: numbers containing the digits 1-9 (each appearing at least once) and no 0's.

Original entry on oeis.org

123456789, 123456798, 123456879, 123456897, 123456978, 123456987, 123457689, 123457698, 123457869, 123457896, 123457968, 123457986, 123458679, 123458697, 123458769, 123458796, 123458967, 123458976, 123459678, 123459687, 123459768, 123459786, 123459867, 123459876, 123465789
Offset: 1

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Author

Keywords

Comments

The first 9! = 362880 terms of this sequence are permutations of the digits 1-9 with a(9!) = 987654321. - Jeremy Gardiner, May 28 2010
First differences are given in A209280 (for the first 9! terms) or in A219664 (for at least as much initial terms). - M. F. Hasler, Mar 03 2013
A230959(a(n)) = 0. - Reinhard Zumkeller, Nov 02 2013
After the first 9! terms, 8! + 7! = 9*7! of the initial terms are repeated with a leading '1' prefixed, cf. formula. However, a(9!+8!+7!) = 1219...3 is followed by 122...9 and permutations of the last 7 digits, before 12314..9. - M. F. Hasler, Jan 08 2020, corrected Aug 11 2022 thanks to a remark from Michael S. Branicky

Crossrefs

Programs

  • PARI
    apply( {A050289(n)=if(n<=7!*81, fromdigits(Vec(numtoperm(9,n-1)))+(n-1)\9!*10^9, "not yet implemented")}, [1..25]) \\ M. F. Hasler, Jan 07 2020, corrected Aug 11 2022
    
  • Python
    from itertools import count, islice, permutations, product
    def c(t): return len(set(t)) == 9
    def t2i(t): return int("".join(map(str, t)))
    def agen():
        yield from (t2i(p) for p in permutations(range(1, 10)))
        for d in count(10):
            yield from (t2i(p) for p in product(range(1, 10), repeat=d) if c(p))
    print(list(islice(agen(), 25))) # Michael S. Branicky, May 30 2022, updated Aug 05 2022

Formula

a(n + 9!) = a(n) + 10^9 for 1 <= n <= 8! + 7!. - M. F. Hasler, Jan 08 2020, corrected Aug 11 2022

Extensions

Name clarified by Michael S. Branicky, Aug 05 2022

A227362 Distinct digits of n arranged in decreasing order.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 21, 31, 41, 51, 61, 71, 81, 91, 20, 21, 2, 32, 42, 52, 62, 72, 82, 92, 30, 31, 32, 3, 43, 53, 63, 73, 83, 93, 40, 41, 42, 43, 4, 54, 64, 74, 84, 94, 50, 51, 52, 53, 54, 5, 65, 75, 85, 95, 60, 61, 62, 63, 64, 65, 6, 76, 86
Offset: 0

Views

Author

Reinhard Zumkeller, Jul 09 2013

Keywords

Comments

a(n) <= 9876543210; a(a(n)) = a(n);
A055642(a(n)) <= 10;
A055642(a(n)) <= A055642(n), A055642(a(n)) = A055642(n) iff A178788(n) = 1;
a(A109303(n)) < A109303(n); a(A009995(n)) = A009995(n); a(A071589(n)) > A071589(n);
a(n) = A151949(n) + A180410(n).

Crossrefs

Programs

  • Haskell
    import Data.List (nub, sort)
    a227362 = read . reverse . sort . nub . show :: Integer -> Integer
    
  • Maple
    a:= n-> parse(cat(sort([{convert(n, base, 10)[]}[]], `>`)[])):
    seq(a(n), n=0..68);  # Alois P. Heinz, Sep 21 2022
  • Mathematica
    f[n_] := FromDigits[Reverse@ Union@ IntegerDigits@ n]; f /@ Range[0, 68] (* Michael De Vlieger, Apr 16 2015, corrected by Robert G. Wilson v *)
  • PARI
    a(n) = {if (n == 0, d = [0], d = digits(n)); eval(subst(Pol(vecsort(d,,12)), x, 10));} \\ Michel Marcus, Apr 16 2015
    
  • PARI
    a(n)=fromdigits(vecsort(digits(n),,12)) \\ Charles R Greathouse IV, Apr 16 2015
    
  • Python
    def A227362(n): return int(''.join(sorted(set(str(n)),reverse=True))) # Chai Wah Wu, Nov 23 2022

A257001 Numbers such that the largest missing digit is a divisor.

Original entry on oeis.org

18, 27, 36, 45, 54, 63, 72, 81, 96, 98, 108, 117, 126, 135, 144, 153, 162, 171, 180, 189, 192, 207, 216, 225, 234, 243, 252, 261, 270, 288, 296, 306, 315, 324, 333, 342, 351, 360, 378, 387, 392, 405, 414, 423, 432, 441, 450, 468, 477, 486, 496, 504, 513, 522
Offset: 1

Views

Author

Keywords

Comments

a(n) mod A000030(A230959(a(n))) = 0.
Pandigital numbers are not terms: A171102, A050278.
The original definition used the phrase "largest absent digit".

Crossrefs

Programs

  • Haskell
    import Data.List ((\\)); import Data.Char (digitToInt)
    a257001 n = a257001_list !! (n-1)
    a257001_list = filter f [1..] where
       f x = h > 0 && mod x h == 0 where h = a000030 $ a230959 x
  • Mathematica
    f[x_]:=Union[Sort[IntegerDigits[x]]];
    d={1,2,3,4,5,6,7,8,9};
    Select[Range[525],And[f[#]!=d,Length[f[#]]<10,IntegerQ[#/Max[Complement[d,f[#]]]]]&] (* Ivan N. Ianakiev, Apr 14 2015 *)
Showing 1-4 of 4 results.