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 21-28 of 28 results.

A293880 Numbers having '20' as substring of their digits.

Original entry on oeis.org

20, 120, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 220, 320, 420, 520, 620, 720, 820, 920, 1020, 1120, 1200, 1201, 1202, 1203, 1204, 1205, 1206, 1207, 1208, 1209, 1220, 1320, 1420, 1520, 1620, 1720, 1820, 1920, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
Offset: 1

Views

Author

M. F. Hasler, Oct 18 2017

Keywords

Comments

Row 20 of A292690 and A293869. A121040 lists the terms which are divisible by 19.

Crossrefs

Cf. A121041, A121022, A121023, A121024, A121025, A121026, A121027, A121028, A121029, A121030, A121031, A121032, A121033, A121034, A121035, A121036, A121037, A121038, A121039, A121040: subsequences of the above, containing only multiples of the pattern p.

Programs

  • Mathematica
    Select[Range[2100],SequenceCount[IntegerDigits[#],{2,0}]>0&] (* Harvey P. Dale, Jul 25 2021 *)
  • PARI
    is_A293880 = has(n, p=20, m=10^#Str(p))=until(p>n\=10, n%m==p&&return(1))

Formula

a(n) ~ n. - Charles R Greathouse IV, Nov 02 2022

A175688 Numbers k with property that arithmetic mean of its digits is both an integer and one of the digits of k.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 102, 111, 120, 123, 132, 135, 147, 153, 159, 174, 195, 201, 204, 210, 213, 222, 231, 234, 240, 243, 246, 258, 264, 285, 306, 312, 315, 321, 324, 333, 342, 345, 351, 354, 357, 360, 369, 375, 396, 402
Offset: 1

Views

Author

Claudio Meller, Aug 09 2010

Keywords

Comments

Subsequence of A061383.
A180160(a(n)) = 0. - Reinhard Zumkeller, Aug 15 2010

Examples

			135 is in the list because (1+3+5)/3 = 3 and 3 is a digit of 135.
		

Crossrefs

Programs

  • Haskell
    a175688 n = a175688_list !! (n-1)
    a175688_list = filter f [0..] where
       f x = m == 0 && ("0123456789" !! avg) `elem` show x
             where (avg, m) = divMod (a007953 x) (a055642 x)
    -- Reinhard Zumkeller, Jun 18 2013
  • Mathematica
    idQ[n_]:=Module[{idn=IntegerDigits[n],m},m=Mean[idn];IntegerQ[m] && MemberQ[idn,m]]; Select[Range[0,500],idQ] (* Harvey P. Dale, Jun 10 2011 *)

Extensions

Edited by Reinhard Zumkeller, Aug 13 2010

A257667 Primes containing a digit 5.

Original entry on oeis.org

5, 53, 59, 151, 157, 251, 257, 353, 359, 457, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 653, 659, 751, 757, 853, 857, 859, 953, 1051, 1151, 1153, 1259, 1451, 1453, 1459, 1511, 1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579
Offset: 1

Views

Author

Vincenzo Librandi, May 03 2015

Keywords

Comments

Subsequence of primes of A011535. - Michel Marcus, May 03 2015
Primes in A062671. - Bruno Berselli, May 03 2015

Crossrefs

Cf. prime numbers containing the string k: A208270 (k=1), A208272 (k=2), A212525 (k=3), this sequence (k=5), A257668 (k=7), A166571 (k=10), A166572 (k=11), A243529 (k=12), A166573 (k=13), A243530 (k=14), A243531 (k=15), A243532 (k=16), A166579 (k=17), A243527 (k=111), A166580 (k=222), A166581 (k=333), A166582 (k=444).
Cf. A011535, A062671, A243531 (subsequence).

Programs

  • Magma
    [p: p in PrimesUpTo(1600) | 5 in Intseq(p)];
    
  • Mathematica
    Select[Prime[Range[250]], ! StringFreeQ[ToString[#], "5"] &]
  • PARI
    forprime(p=1, 1600, if(vecsearch(vecsort(digits(p)), 5), print1(p, ", "))) \\ Derek Orr, May 05 2015; corrected by Michel Marcus, Oct 30 2023
  • Sage
    [p for p in primes(1600) if 5 in p.digits(base=10)] # Bruno Berselli, May 03 2015
    

Formula

a(n) ~ n log n. - Charles R Greathouse IV, Nov 01 2022

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
    

A043510 Numbers having two 5's in base 10.

Original entry on oeis.org

55, 155, 255, 355, 455, 505, 515, 525, 535, 545, 550, 551, 552, 553, 554, 556, 557, 558, 559, 565, 575, 585, 595, 655, 755, 855, 955, 1055, 1155, 1255, 1355, 1455, 1505, 1515, 1525, 1535, 1545, 1550, 1551, 1552, 1553, 1554, 1556
Offset: 1

Views

Author

Keywords

Crossrefs

Subsequence of A011535.

Programs

  • Mathematica
    Select[Range[1600],DigitCount[#,10,5]==2&] (* Harvey P. Dale, Sep 01 2021 *)

A043511 Numbers having three 5's in base 10.

Original entry on oeis.org

555, 1555, 2555, 3555, 4555, 5055, 5155, 5255, 5355, 5455, 5505, 5515, 5525, 5535, 5545, 5550, 5551, 5552, 5553, 5554, 5556, 5557, 5558, 5559, 5565, 5575, 5585, 5595, 5655, 5755, 5855, 5955, 6555, 7555, 8555, 9555, 10555
Offset: 1

Views

Author

Keywords

Crossrefs

Subsequence of A011535.

Programs

  • Mathematica
    Select[Range[555,11000],DigitCount[#,10,5]==3&] (* Harvey P. Dale, May 31 2021 *)

A043512 Numbers having four 5's in base 10.

Original entry on oeis.org

5555, 15555, 25555, 35555, 45555, 50555, 51555, 52555, 53555, 54555, 55055, 55155, 55255, 55355, 55455, 55505, 55515, 55525, 55535, 55545, 55550, 55551, 55552, 55553, 55554, 55556, 55557, 55558, 55559, 55565, 55575
Offset: 1

Views

Author

Keywords

Crossrefs

Subsequence of A011535.

A124694 Sets of digits such that the product of the digits is 10 times the sum of the digits. Each set is arranged as a number with nondecreasing digits.

Original entry on oeis.org

459, 1566, 2259, 2355, 11558, 12445, 111567, 112356, 122245, 1113345, 1222225, 11111568, 11112357, 11112455, 11122335, 111122255, 1111111569, 1111112358, 11111111578, 11111112456, 111111112359, 111111112555, 111111113445
Offset: 1

Views

Author

Tanya Khovanova, Dec 25 2006

Keywords

Comments

4*5*9 = 180 and 4 + 5 + 9 = 18.
Each term must include the digit 5, so it is a subsequence of A011535. - Chai Wah Wu, Dec 08 2015

Crossrefs

A062043 (Numbers for which the product of the digits is 10 times their sum) is created by permuting digits in every number of this sequence.

Programs

  • Mathematica
    FromDigits /@ DeleteDuplicates@ Map[Sort, IntegerDigits@ Select[Range[10^7], Times @@ # == 10 Total@ # &@ IntegerDigits@ # &]] (* Michael De Vlieger, Dec 09 2015 *)

Extensions

Extended by D. S. McNeil, Dec 16 2010
Previous Showing 21-28 of 28 results.