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.

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A115940 Pandigital (meaning every digit appears exactly once) triangular numbers.

Original entry on oeis.org

1062489753, 1239845706, 1256984730, 1520843976, 1539264870, 1597283460, 1684930275, 1952843760, 1957346028, 1978236450, 2197480365, 2367098415, 2418079653, 2503948761, 2634980715, 2718609453, 2735891406, 2750483196
Offset: 1

Views

Author

Giovanni Resta, Feb 06 2006

Keywords

Comments

There are 82 such numbers, the largest being T(138959)=9654871320.
The sequence of pandigital binomial coefficients C(m,k) with k>1 contains 84 numbers, these 82 triangular terms of the form C(m,2) and only two other ones C(595,4) = 5169738420 and C(253,5) = 8301429675 (see link). - Bernard Schott, Apr 15 2022

Examples

			T(46097)=1062489753.
		

Crossrefs

A116670 Numbers with all but one decimal digit.

Original entry on oeis.org

102345678, 102345679, 102345687, 102345689, 102345697, 102345698, 102345768, 102345769, 102345786, 102345789, 102345796, 102345798, 102345867, 102345869, 102345876, 102345879, 102345896, 102345897, 102345967, 102345968, 102345976, 102345978, 102345986
Offset: 1

Views

Author

Rick L. Shepherd, Feb 22 2006

Keywords

Comments

More precisely, each term has exactly nine distinct decimal digits any of which may occur more than once. Leading zeros are not permitted.

Examples

			a(1) = 102345678 as all decimal digits but 9 appear and there is no smaller number with only one missing digit.
		

Crossrefs

Cf. A050278 (pandigital numbers).

Programs

  • Mathematica
    Select[Range[10^8, 10^8 + 3000000], Length[Union[IntegerDigits[#]]] == 9 &] (* T. D. Noe, Dec 05 2012 *)

Extensions

Offset corrected by Charles R Greathouse IV, Feb 15 2017

A171744 a(n) is the smallest exponent such that prime(n)^k is pandigital in base 10.

Original entry on oeis.org

68, 39, 19, 18, 23, 22, 14, 17, 14, 12, 11, 13, 11, 13, 12, 13, 11, 14, 10, 15, 14, 13, 9, 11, 13, 9, 15, 14, 13, 12, 11, 15, 10, 7, 12, 9, 12, 10, 11, 8, 11, 8, 12, 11, 13, 13, 10, 12, 10, 8, 11, 12, 9, 7, 6, 7, 8, 12, 8, 8, 7, 7, 10, 9, 9, 6, 9, 10, 9, 10
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Dec 17 2009

Keywords

Comments

A pandigital number is an integer that in a given base has among its significant digits each digit used in the base at least once.

Examples

			2^68 = 295147905179352825856 (21 digits), 3^39 = 4052555153018976267 (19)
5^19 = 19073486328125 (14), 7^18 = 1628413597910449 (16), 11^23 = 895430243255237372246531 (24)
13^22 = 3211838877954855105157369 (25), 17^14 = 168377826559400929 (18)
19^17 = 5480386857784802185939 (22), 23^14 = 11592836324538749809 (20)
29^12 = 353814783205469041 (18), 31^11 = 25408476896404831 (17)
37^13 = 243569224216081305397 (21), 41^11 = 550329031716248441 (18)
43^13 = 1718264124282290785243 (22), 47^12 = 116191483108948578241 (21)
53^13 = 26036721925606486195973 (23), 59^11 = 30155888444737842659 (20)
61^14 = 9876832533361318095112441 (25), 67^10 = 1822837804551761449 (19)
71^15 = 5873205959385493353867330551 (28), 73^14 = 122045014039746588673695409 (23)
79^13 = 4668229371502258117133839 (25), 83^9 = 186940255267540403 (18)
89^11 = 2775173073766990340489 (22), 97^13 = 67302709016557486028618977 (26)
101^9 = 1093685272684360901 (19), 103^15 = 1557967416600764580522382952407 (31)
107^14 = 25785341502012466393542552649 (29), 109^13 = 306580461214335498944273629 (27)
113^12 = 4334523100191686738306881 (25), 127^11 = 138624799340320978519423 (24)
		

References

  • E.I. Ignatjew, Mathematische Spielereien, Urania Verlag Leipzig-Jena-Berlin, 2. Auflage 1982.
  • Helmut Kracke, Mathe-musische Knobelisken, Duemmler Bonn, 2. Auflage 1983.

Crossrefs

Programs

  • Mathematica
    sepan[n_]:=Module[{p=Prime[n],k=1},While[Min[DigitCount[p^k]]==0,k++];k]; Array[sepan,100] (* Harvey P. Dale, Aug 03 2019 *)
  • PARI
    a(n) = {my(k=1, p=prime(n)); while(#Set(digits(p^k))<10, k++); k; } \\ Jinyuan Wang, Aug 14 2020

Extensions

Edited by Charles R Greathouse IV, Aug 02 2010
Corrected and extended by Harvey P. Dale, Aug 03 2019

A187565 Numbers divisible by at least eight of their digits, different and >1.

Original entry on oeis.org

1234759680, 1234857960, 1234895760, 1234958760, 1235487960, 1235679480, 1235976840, 1236795840, 1237569480, 1237589640, 1237594680, 1237695480, 1237894560, 1238549760, 1238574960, 1238597640, 1238975640, 1239547680, 1239567840, 1239756840, 1239784560, 1239847560, 1239857640, 1243579680, 1243589760, 1243879560, 1243957680, 1245378960, 1245973680, 1245983760
Offset: 1

Views

Author

Zak Seidov, Mar 11 2011

Keywords

Comments

First 11460 terms are pandigital numbers (A050278).
Asymptotic density 1/2520 = 0.000396.... - Charles R Greathouse IV, Mar 11 2011
11460 terms up to 10^10, 299275 terms up to 10^11, 6224794 terms up to 10^12. - Charles R Greathouse IV, Mar 11 2011

Crossrefs

Subsequence of A187551 (numbers divisible by at least seven ...).

Programs

  • Mathematica
    numdig = 8; Select[Range[1245983760], Length[(u = Union[Select[IntegerDigits[#], #1 > 1 &]])] >= numdig && Plus @@ (Boole@Divisible[#, u]) >= numdig &] (* Amiram Eldar, Aug 30 2020 *)
  • PARI
    s(n) = my(res=Set(digits(n)));select(x->x>1,res)
    is(n) = my(d=s(n));if(#d < 8, return(0)); sum(i=1, #d, n%d[i]==0) >= 8 \\ David A. Corneth, Aug 30 2020

A218019 Integers in which the number of distinct base-10 digits is 7.

Original entry on oeis.org

1023456, 1023457, 1023458, 1023459, 1023465, 1023467, 1023468, 1023469, 1023475, 1023476, 1023478, 1023479, 1023485, 1023486, 1023487, 1023489, 1023495, 1023496, 1023497, 1023498, 1023546, 1023547, 1023548, 1023549, 1023564, 1023567, 1023568, 1023569
Offset: 1

Views

Author

Jonathan Vos Post, Dec 04 2012

Keywords

Comments

This is to A031969 as 7 is to 4. This is the 7th row of the array A(k,n) = n-th number in which the number of distinct base-10 digits is k. A031969 is the 4th row. A220063 is the 5th row. A220076 is the 6th row. Pandigital numbers A050278 is the 10th row. The subsequence of primes begins: 1023467, 1023487.

Crossrefs

Programs

  • Mathematica
    Select[Range[1000000, 1030000], Length[Union[IntegerDigits[#]]] == 7 &] (* T. D. Noe, Dec 04 2012 *)

A116667 Greatest digit not used in n (or 10 if n is pandigital).

Original entry on oeis.org

9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 7, 8, 8, 8, 8, 8, 8, 8, 8, 7, 8, 9, 9, 9, 9, 9
Offset: 0

Views

Author

Rick L. Shepherd, Feb 22 2006

Keywords

Comments

a(A050278(1)) = a(1023456789) = 10, the first term with that value, as 1023456789 is the first base 10 pandigital number.

Examples

			a(89) = 7 because decimal digits 8 and 9 are both used in 89.
		

Crossrefs

Cf. A067898 (least digit not used in n), A050278 (pandigital numbers).

Programs

  • Python
    def A116667(n):
        s = set(str(n))
        for i in range(9,-1,-1):
            if str(i) not in s:
                return i
        return 10 # Chai Wah Wu, Apr 13 2024

A178775 Smallest prime factors of zerofull restricted pandigital numbers.

Original entry on oeis.org

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

Views

Author

Reinhard Zumkeller, Jun 11 2010

Keywords

Comments

a(n) = A020639(A050278(n)); 2 <= a(n) <= 3.
a(n) is 2 1653120 times and 3 1612800 times, making the average value 202/81 = 2.493.... [Charles R Greathouse IV, Sep 09 2011]

Examples

			A050278(1)=1023456789=3*3*3*3*2221*5689 --> a(1)=3;
A050278(10)=1023457896=2*2*2*3*3*3*59*80309 --> a(10)=2;
A050278(100)=1023495786=2*3*3*739*76943 --> a(100)=2;
A050278(1000)=1024658793=3*3*113850977 --> a(1000)=3.
		

Formula

a(n) = 2 + A000035(A050278(n)).

Extensions

Edited by Charles R Greathouse IV, Aug 02 2010

A252490 Numbers whose set of digits is simply connected, with 9 and 0 considered as neighbors.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 21, 22, 23, 32, 33, 34, 43, 44, 45, 54, 55, 56, 65, 66, 67, 76, 77, 78, 87, 88, 89, 90, 98, 99, 100, 101, 102, 109, 110, 111, 112, 120, 121, 122, 123, 132, 190, 201, 210, 211, 212, 213, 221, 222, 223, 231, 232, 233, 234, 243, 312, 321, 322, 323, 324, 332, 333, 334, 342, 343, 344, 345, 354, 423, 432
Offset: 1

Views

Author

M. F. Hasler, Dec 24 2014

Keywords

Comments

The set of digits must consist of a single run without "holes", but for a cyclic topology where 9 and 0 are seen as neighbors.
A superset of A134336. Namely, numbers in A134336 or such that the complement of their digits in {0,...,9} satisfies the criterion of A134336.

Crossrefs

Cf. A032981, A050278, A033075 (a subsequence), A010785, A108965, A134336 (a subsequence).

Programs

  • PARI
    is(n)=vecmax(if((d=Set(digits(n)))[1],d,d=setminus(vector(9,i,i),d)))-vecmin(d)==#d-1

A253172 Numbers n = p * q, where n, p, and q together contain all 10 digits at least once.

Original entry on oeis.org

15628, 15678, 16038, 17082, 17820, 19084, 20457, 20748, 20754, 21658, 24507, 24587, 25704, 26910, 26970, 27096, 27504, 27690, 28156, 28651, 29076, 29370, 29670, 29706, 29730, 30956, 30972, 30976, 32890, 32970, 34056, 34902, 34986, 35046, 35074, 35096, 35496, 35690, 36092, 36490, 36508, 36950, 36970, 36972, 37092, 37096, 37290, 37590, 37690, 37908, 38870, 39026, 39720, 39760, 40587, 40596
Offset: 1

Views

Author

Randy L. Ekl, Dec 28 2014

Keywords

Comments

All pandigital numbers (cf. A171102) belong to this sequence; therefore A050288(1) = 10123457689 is the smallest prime term. - Reinhard Zumkeller, Dec 29 2014

Examples

			a(1) is 15628 = 4 * 3907, using all 10 digits.
a(8) is 20748 = 13 * 1596 (note duplicate 1, which is ok in this sequence).
a(3) is 16038 = 27 * 594, and also 16038 = 54 * 297; two different solutions for a(3).
		

Crossrefs

Cf. A195814, which restricts sequence terms along with their factors to exactly 10 digits, and thus has a finite number of terms.
Cf. A027750, subsequences: A050278, A171102, A050288.

Programs

  • Haskell
    import Data.List (nub, sort)
    a253172 n = a253172_list !! (n-1)
    a253172_list = filter f [2..] where
       f x = g divs $ reverse divs where
             g (d:ds) (q:qs) = d <= q &&
               (sort (nub $ xs ++ show d ++ show q) == decs || g ds qs)
             xs = show x
             divs = a027750_row x
       decs = "0123456789"
    -- Reinhard Zumkeller, Dec 29 2014
  • PARI
    isokpq(n) = {fordiv(n, d, digs = digits(n); if ( d <= sqrtint(n), digs = concat(digs, digits(d)); digs = concat(digs, digits(n/d)); if (#Set(digs) == 10, return(1));););}
    lista(nn) = {for(n=2, nn, if (isokpq(n), print1(n, ", ")););} \\ Michel Marcus, Dec 29 2014
    

A266279 Nonnegative integers where all occurring digits occur with equal frequency.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67
Offset: 1

Views

Author

Felix Fröhlich, Dec 26 2015

Keywords

Comments

The set of terms of this sequence is a superset of each of the sets of terms of A050278 and A082810.
Except for i = 1, A261315(i) gives the number of existing n such that A055642(a(n)) = i.

Examples

			1122 is a term of the sequence, since all occurring digits occur twice.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[0, 67], Length@ Union[DigitCount[#] /. 0 -> Nothing] == 1 &] (* Michael De Vlieger, Jan 06 2016 *)
  • PARI
    digitcount(n) = my(d=digits(n), v=vector(10)); for(x=0, 9, for(k=1, #d, if(d[k]==x, v[x+1]++))); v
    is(n) = my(c=digitcount(n), k=0); for(i=1, #c, if(k==0 && c[i]!=0, k=c[i]); if(k!=0 && c[i]!=0, if(k!=c[i], return(0)))); return(1)
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