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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A283608 Numbers whose largest decimal digit is 5.

Original entry on oeis.org

5, 15, 25, 35, 45, 50, 51, 52, 53, 54, 55, 105, 115, 125, 135, 145, 150, 151, 152, 153, 154, 155, 205, 215, 225, 235, 245, 250, 251, 252, 253, 254, 255, 305, 315, 325, 335, 345, 350, 351, 352, 353, 354, 355, 405, 415, 425, 435, 445, 450, 451, 452, 453, 454
Offset: 1

Views

Author

Jaroslav Krizek, Mar 19 2017

Keywords

Comments

Numbers n such that A054055(n) = 5.
Number of terms less than 10^n is 6^n - 5^n.
Subsequence of A011535. - David A. Corneth, Mar 25 2017
Prime terms are in A106097.

Crossrefs

Cf. Sequences of numbers whose largest decimal digit is k (for k = 1..9): A007088 (k = 1), A277964 (k = 2), A277965 (k = 3), A277966 (k = 4), this sequence (k = 5), A283609 (k = 6), A283610 (k = 7), A283611 (k = 8), A011539 (k = 9).

Programs

  • GAP
    Filtered([1..500],n->Maximum(ListOfDigits(n))=5); # Muniru A Asiru, Feb 27 2019
  • Magma
    [n: n in [1..100000] | Maximum(Setseq(Set(Sort(&cat[Intseq(n)])))) eq 5];
    
  • Mathematica
    Select[Range[1000], Max[IntegerDigits[#]] == 5 &] (* Giovanni Resta, Mar 19 2017 *)
  • PARI
    for(n=1, 500, if(vecmax(digits(n))==5, print1(n,", "))) \\ Indranil Ghosh, Mar 19 2017
    
  • PARI
    nxt(n) = {my(d = digits(n), i, j=0, t=0); forstep(i=#d,1,-1, if(d[i]!=5, j=i; break)); if(j>0, d[j]++; if(d[j]==5, for(k=j+1,#d,d[k]=0)); if(j<#d && d[j+1]==5, for(k=j+1,#d-1,d[k]=0)); for(k=1,j-1, if(d[k]==5,for(i=j+1, #d, d[i] = 0);break)), d = vector(#d+1); d[1]=1; d[#d]=5);sum(i=1, #d, d[i]*10^(#d-i))} \\ David A. Corneth, Mar 25 2017
    
  • Python
    from sympy.ntheory.factor_ import digits
    print([n for n in range(1, 501) if max(digits(n)[1:])==5]) # Indranil Ghosh, Mar 19 2017
    

A283609 Numbers whose largest decimal digit is 6.

Original entry on oeis.org

6, 16, 26, 36, 46, 56, 60, 61, 62, 63, 64, 65, 66, 106, 116, 126, 136, 146, 156, 160, 161, 162, 163, 164, 165, 166, 206, 216, 226, 236, 246, 256, 260, 261, 262, 263, 264, 265, 266, 306, 316, 326, 336, 346, 356, 360, 361, 362, 363, 364, 365, 366, 406, 416, 426
Offset: 1

Views

Author

Jaroslav Krizek, Mar 19 2017

Keywords

Comments

Numbers n such that A054055(n) = 6.
Number of terms less than 10^n is 7^n - 6^n.
Prime terms are in A106096.

Crossrefs

Cf. Sequences of numbers whose largest decimal digit is k (for k = 1..9): A007088 (k = 1), A277964 (k = 2), A277965 (k = 3), A277966 (k = 4), A283608 (k = 5), this sequence (k = 6), A283610 (k = 7), A283611 (k = 8), A011539 (k = 9).

Programs

  • GAP
    Filtered([1..500],n->Maximum(ListOfDigits(n))=6); # Muniru A Asiru, Mar 01 2019
  • Magma
    [n: n in [1..100000] | Maximum(Setseq(Set(Sort(&cat[Intseq(n)])))) eq 6]
    
  • Mathematica
    Select[Range[1000], Max[IntegerDigits[#]] == 6 &] (* Giovanni Resta, Mar 19 2017 *)
  • PARI
    for(n=1, 500, if(vecmax(digits(n))==6, print1(n,", "))) \\ Indranil Ghosh, Mar 19 2017
    
  • Python
    from sympy.ntheory.factor_ import digits
    print([n for n in range(1, 501) if max(digits(n)[1:])==6]) # Indranil Ghosh, Mar 19 2017
    

A283610 Numbers n whose largest decimal digit is 7.

Original entry on oeis.org

7, 17, 27, 37, 47, 57, 67, 70, 71, 72, 73, 74, 75, 76, 77, 107, 117, 127, 137, 147, 157, 167, 170, 171, 172, 173, 174, 175, 176, 177, 207, 217, 227, 237, 247, 257, 267, 270, 271, 272, 273, 274, 275, 276, 277, 307, 317, 327, 337, 347, 357, 367, 370, 371, 372
Offset: 1

Views

Author

Jaroslav Krizek, Mar 19 2017

Keywords

Comments

Numbers n such that A054055(n) = 7.
Number of terms less than 10^n is 8^n - 7^n.
Prime terms are in A106095.

Crossrefs

Cf. Sequences of numbers n whose largest decimal digit is k (for k = 1 - 9): A007088 (k = 1), A277964 (k = 2), A277965 (k = 3), A277966 (k = 4), A283608 (k = 5), A283609 (k = 6), this sequence (k = 7), A283611 (k = 8), A011539 (k = 9).

Programs

  • GAP
    Filtered([1..380],n->Maximum(ListOfDigits(n))=7); # Muniru A Asiru, Feb 27 2019
  • Magma
    [n: n in [1..100000] | Maximum(Setseq(Set(Sort(&cat[Intseq(n)])))) eq 7]
    
  • Mathematica
    Select[Range[1000], Max[IntegerDigits[#]] == 7 &] (* Giovanni Resta, Mar 19 2017 *)
  • PARI
    for(n=1, 500, if(vecmax(digits(n))==7, print1(n,", "))) \\ Indranil Ghosh, Mar 19 2017
    
  • Python
    from sympy.ntheory.factor_ import digits
    [n for n in range(1, 401) if max(digits(n)[1:]) == 7]  # Indranil Ghosh, Mar 19 2017
    

A283611 Numbers whose largest decimal digit is 8.

Original entry on oeis.org

8, 18, 28, 38, 48, 58, 68, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 108, 118, 128, 138, 148, 158, 168, 178, 180, 181, 182, 183, 184, 185, 186, 187, 188, 208, 218, 228, 238, 248, 258, 268, 278, 280, 281, 282, 283, 284, 285, 286, 287, 288, 308, 318, 328, 338, 348
Offset: 1

Views

Author

Jaroslav Krizek, Mar 19 2017

Keywords

Comments

Numbers n such that A054055(n) = 8.
Number of terms less than 10^n is 9^n - 8^n.
Prime terms are in A106094.

Crossrefs

Cf. Sequences of numbers whose largest decimal digit is k (for k = 1..9): A007088 (k = 1), A277964 (k = 2), A277965 (k = 3), A277966 (k = 4), A283608 (k = 5), A283609 (k = 6), A283610 (k = 7), this sequence (k = 8), A011539 (k = 9).

Programs

  • GAP
    Filtered([1..400],n->Maximum(ListOfDigits(n))=8); # Muniru A Asiru, Mar 01 2019
  • Magma
    [n: n in [1..100000] | Maximum(Setseq(Set(Sort(&cat[Intseq(n)])))) eq 8]
    
  • Maple
    f:= proc(n) local L;
      L:= convert(n,base,9);
      if not has(L,8) then return NULL fi;
      add(L[i]*10^(i-1),i=1..nops(L))
    end proc:
    map(f, [$8..1000]); # Robert Israel, Mar 27 2017
  • Mathematica
    Select[Range@ 350, Max@ IntegerDigits@ # == 8 &] (* Michael De Vlieger, Mar 25 2017 *)
  • PARI
    isok(n) = vecmax(digits(n)) == 8; \\ Michel Marcus, Mar 25 2017
    

A297418 a(n) is the smallest positive number not yet in the sequence that contains the largest digit in a(n-1); a(1)=0.

Original entry on oeis.org

0, 10, 1, 11, 12, 2, 20, 21, 22, 23, 3, 13, 30, 31, 32, 33, 34, 4, 14, 24, 40, 41, 42, 43, 44, 45, 5, 15, 25, 35, 50, 51, 52, 53, 54, 55, 56, 6, 16, 26, 36, 46, 60, 61, 62, 63, 64, 65, 66, 67, 7, 17, 27, 37, 47, 57, 70, 71, 72, 73, 74, 75, 76, 77, 78, 8, 18, 28, 38, 48, 58, 68, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 9, 19, 29
Offset: 1

Views

Author

Enrique Navarrete, Dec 29 2017

Keywords

Comments

Once the digit 9 is introduced in a(82)=89, all following terms must contain a 9.
The sequence contains no fixed points.
Analog sequence formed by taking the smallest digit from a(n-1) is A011540.

Crossrefs

Programs

  • Mathematica
    a[n_] := a[n] = Block[{k = 1, s = Union[ IntegerDigits[ a[n -1]]][[-1]], t = Array[a, n - 1]}, While[ MemberQ[t, k] || !MemberQ[ IntegerDigits@ k, s], k++]; k]; a[1] = 0; Array[a, 72] (* Robert G. Wilson v, Dec 30 2017 *)
    Nest[Append[#, Block[{m = Max@ IntegerDigits@ Last@ #, k}, k = m; While[Nand[FreeQ[#, k], MemberQ[IntegerDigits[k], m]], k++]; k]] &, {0}, 84] (* Michael De Vlieger, Dec 30 2017 *)
  • PARI
    first(n) = my(res = vector(n)); for(x=2, n, if(x == 2, res[x] = 10, for(i=1, +oo, if(!setsearch(Set(res), i) && setsearch(Set(digits(i)), vecmax(digits(res[x-1]))), res[x] = i; break())))); res \\ Iain Fox, Dec 31 2017

Formula

For n >= 91, a(n) = A011539(n - 81). - Iain Fox, Dec 31 2017

A245877 Primes p such that p - d and p + d are also primes, where d is the largest digit of p.

Original entry on oeis.org

263, 563, 613, 653, 1613, 1663, 3463, 4643, 5563, 5653, 6263, 6323, 12653, 13463, 14633, 16063, 16223, 21163, 21563, 25463, 26113, 30643, 32063, 33623, 36313, 41263, 41603, 44263, 53623, 54623, 56003, 60133, 61553, 62213, 62633, 64013, 65413, 105613, 106213
Offset: 1

Views

Author

Colin Barker, Aug 05 2014

Keywords

Comments

Intersection of A245742 and A245743.
The largest digit of a(n) is 6, and the least significant digit of a(n) is 3.
Intersection of A006489, A011536, and complements of A011537, A011538, A011539. - Robert Israel, Aug 05 2014

Examples

			The prime 263 is in the sequence because 263 - 6 = 257 and 263 + 6 = 269 are both primes.
		

Crossrefs

Programs

  • Mathematica
    pdpQ[n_]:=Module[{m=Max[IntegerDigits[n]]},AllTrue[n+{m,-m},PrimeQ]]; Select[ Prime[Range[11000]],pdpQ] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jan 13 2017 *)
  • PARI
    select(p->d=vecsort(digits(p),,4)[1]; isprime(p-d) && isprime(p+d), primes(20000))
    
  • Python
    import sympy
    from sympy import prime
    from sympy import isprime
    for n in range(1,10**5):
      s=prime(n)
      lst = []
      for i in str(s):
        lst.append(int(i))
      if isprime(s+max(lst)) and isprime(s-max(lst)):
        print(s,end=', ')
    # Derek Orr, Aug 13 2014

A043526 Numbers having two 9's in base 10.

Original entry on oeis.org

99, 199, 299, 399, 499, 599, 699, 799, 899, 909, 919, 929, 939, 949, 959, 969, 979, 989, 990, 991, 992, 993, 994, 995, 996, 997, 998, 1099, 1199, 1299, 1399, 1499, 1599, 1699, 1799, 1899, 1909, 1919, 1929, 1939, 1949, 1959, 1969
Offset: 1

Views

Author

Keywords

Crossrefs

Subsequence of A011539.

Programs

  • Mathematica
    Select[Range[2000],DigitCount[#,10,9]==2&] (* Harvey P. Dale, May 08 2018 *)

A043527 Numbers having three 9's in base 10.

Original entry on oeis.org

999, 1999, 2999, 3999, 4999, 5999, 6999, 7999, 8999, 9099, 9199, 9299, 9399, 9499, 9599, 9699, 9799, 9899, 9909, 9919, 9929, 9939, 9949, 9959, 9969, 9979, 9989, 9990, 9991, 9992, 9993, 9994, 9995, 9996, 9997, 9998, 10999
Offset: 1

Views

Author

Keywords

Crossrefs

Subsequence of A011539.

A043528 Numbers having four 9's in base 10.

Original entry on oeis.org

9999, 19999, 29999, 39999, 49999, 59999, 69999, 79999, 89999, 90999, 91999, 92999, 93999, 94999, 95999, 96999, 97999, 98999, 99099, 99199, 99299, 99399, 99499, 99599, 99699, 99799, 99899, 99909, 99919, 99929, 99939
Offset: 1

Views

Author

Keywords

Crossrefs

Subsequence of A011539.

Programs

  • Mathematica
    Select[Range[100000],DigitCount[#,10,9]==4&] (* Harvey P. Dale, Aug 22 2011 *)

A092361 Palindromic numbers containing one or more odd digits.

Original entry on oeis.org

1, 3, 5, 7, 9, 11, 33, 55, 77, 99, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 212, 232, 252, 272, 292, 303, 313, 323, 333, 343, 353, 363, 373, 383, 393, 414, 434, 454, 474, 494, 505, 515, 525, 535, 545, 555, 565, 575, 585, 595, 616, 636, 656, 676, 696
Offset: 1

Views

Author

Michael Joseph Halm, Mar 19 2004

Keywords

Comments

Begins to differ from the odd palindromic numbers, A029950, in the 21st term.

Examples

			a(21) = 212 because it is the 21st palindromic number with an odd digit, the first even one
		

Crossrefs

Programs

  • Mathematica
    Select[Range[1000],PalindromeQ[#]&&AnyTrue[IntegerDigits[#],OddQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 24 2021 *)

Extensions

Corrected and definition clarified by Harvey P. Dale, May 24 2021
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