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.

A116695 Digit not appearing in A116670(n).

Original entry on oeis.org

9, 8, 9, 7, 8, 7, 9, 8, 9, 6, 8, 6, 9, 7, 9, 6, 7, 6, 8, 7, 8, 6, 7, 6, 9, 8, 9, 7, 8, 7, 9, 8, 9, 5, 8, 5, 9, 7, 9, 5, 7, 5, 8, 7, 8, 5, 7, 5, 9, 8, 9, 6, 8, 6, 9, 8, 9, 5, 8, 5, 9, 6, 9, 5, 6, 5, 8, 6, 8, 5, 6, 5, 9, 7, 9, 6, 7, 6, 9, 7, 9, 5, 7, 5, 9, 6, 9, 5, 6, 5, 7, 6, 7, 5, 6, 5, 8, 7, 8, 6, 7, 6, 8, 7, 8
Offset: 1

Views

Author

Rick L. Shepherd, Feb 23 2006

Keywords

Examples

			a(1) = 9 as all decimal digits but 9 appear in A116670(1) = 102345678.
		

Crossrefs

Cf. A116670 (Numbers with all but one decimal digit).

Extensions

Offset adapted to the offset of A116670 by Alois P. Heinz, Apr 08 2022

A219743 Number for which the number of distinct base 10 digits is 8.

Original entry on oeis.org

10234567, 10234568, 10234569, 10234576, 10234578, 10234579, 10234586, 10234587, 10234589, 10234596, 10234597, 10234598, 10234657, 10234658, 10234659, 10234675, 10234678, 10234679, 10234685, 10234687, 10234689, 10234695, 10234697, 10234698
Offset: 1

Views

Author

Jonathan Vos Post, Dec 05 2012

Keywords

Crossrefs

Cf. A010785 (1 digits), A031955 (2 digits), A031962 (3 digits), A031969 (4 digits), A031987 (5 digits), A220076 (6 digits), A218019 (7 digits), A116670 (9 digits), A171102 (10 digits).

Programs

  • Mathematica
    Select[Range[10^7, 10^7 + 1000000], Length[Union[IntegerDigits[#]]] == 8 &] (* T. D. Noe, Dec 05 2012 *)

Extensions

Corrected and extended by T. D. Noe, Dec 05 2012

A337127 Table with 10 columns read by rows: T(n, k) is the number of n-digit positive integers with exactly k distinct base 10 digits (0 < k <= 10).

Original entry on oeis.org

9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 81, 0, 0, 0, 0, 0, 0, 0, 0, 9, 243, 648, 0, 0, 0, 0, 0, 0, 0, 9, 567, 3888, 4536, 0, 0, 0, 0, 0, 0, 9, 1215, 16200, 45360, 27216, 0, 0, 0, 0, 0, 9, 2511, 58320, 294840, 408240, 136080, 0, 0, 0, 0, 9, 5103, 195048, 1587600, 3810240, 2857680, 544320, 0, 0, 0
Offset: 1

Views

Author

Stefano Spezia, Aug 17 2020

Keywords

Examples

			The table T(n, k) begins:
9     0      0       0       0       0  0  0  0  0
9    81      0       0       0       0  0  0  0  0
9   243    648       0       0       0  0  0  0  0
9   567   3888    4536       0       0  0  0  0  0
9  1215  16200   45360   27216       0  0  0  0  0
9  2511  58320  294840  408240  136080  0  0  0  0
...
		

Crossrefs

Cf. A010734, A048993, A052268 (row sums), A073531 (diagonal), A180599 (k = 1), A335843 (k = 2), A337313 (k = 3).

Programs

  • Mathematica
    T[n_,k_]:=9Pochhammer[11-k,k-1]/k!*n!*Coefficient[Series[(Exp[x]-1)^k,{x,0,n}],x,n]; Table[T[n,k],{n,7},{k,10}]//Flatten

Formula

T(n, k) = 9*Pochhammer(11-k, k-1)*n! * [x^n] (exp(x) - 1)^k/k!.
T(n, k) = 9*Pochhammer(11-k, k-1) * [x^n] x^k/Product_{j=1..k} (1-j*x).
T(n, k) = 9*Pochhammer(11-k, k-1)*S2(n, k) where S2(n, k) = A048993(n, k) are the Stirling numbers of the 2nd kind.

A227795 For each base, b, beginning with binary, the number of (b-1)-digit primes with one copy of each digit save one.

Original entry on oeis.org

0, 3, 1, 9, 52, 283, 2113, 16142, 145227, 1359133, 15000161, 172888810, 2217146126
Offset: 2

Views

Author

James G. Merickel, Sep 23 2013

Keywords

Comments

Note that only decimal 2, 11 and 19 are representable in some base using a copy of each digit in that base (base 2 for the first and base 3 for the others), as a number written in base b with a single copy of each digit is congruent to either 0 or (b-1)/2 modulo b-1.

Examples

			In base 3, 10, 12 and 21 are primes: Decimal 3, 5 and 7.  In base 4, of the possibilities only 103 is prime: Decimal 19.
		

Crossrefs

Programs

  • PARI
    \\ Starts at base 4 and prints in form 'base:count', bases 2 and 3 done by hand.
    {
    b=4;while(1,
    c=0;for(i=1,b!,perm=numtoperm(b,i);
    if(perm[b-1]!=1,
    if(gcd(b,perm[1]-1)==1,
    if(gcd(b-1,perm[b]-1)==1,
    n=sum(j=1,b-1,(perm[j]-1)*b^(j-1));
    if(ispseudoprime(n),c++)))));
    print1(b":"c"\n");b++)
    }

Extensions

a(14) added by James G. Merickel, Oct 14 2013
Showing 1-4 of 4 results.