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 1-3 of 3 results.

A295005 Numbers n such that the largest digit of n^2 is 5.

Original entry on oeis.org

5, 15, 35, 39, 45, 50, 55, 65, 71, 105, 112, 115, 145, 150, 155, 185, 188, 205, 211, 229, 235, 335, 350, 365, 368, 388, 389, 390, 450, 461, 485, 495, 500, 501, 502, 505, 550, 579, 585, 595, 635, 650, 652, 665, 671, 710, 711, 715, 718, 729, 735, 745, 1005, 1015, 1050
Offset: 1

Views

Author

M. F. Hasler, Nov 12 2017

Keywords

Examples

			39 is in this sequence because 39^2 = 1521 has 5 as largest digit.
		

Crossrefs

Cf. A295015 (the corresponding squares), A277959 .. A277961 (same for digit 2 .. 4), A295006 .. A295009 (same for digit 6 .. 9).
Cf. A000290 (the squares).

Programs

  • Mathematica
    Select[Sqrt[ #]&/@(FromDigits/@Select[Tuples[ Range[ 0,5],7],Max[#] == 5&]),IntegerQ] (* Harvey P. Dale, Sep 23 2021 *)
  • PARI
    select( is_A295005(n)=n&&vecmax(digits(n^2))==5 , [0..999]) \\ The "n&&" avoids an error message for n=0.
    
  • Python
    def aupto(limit):
      alst = []
      for k in range(1, limit+1):
        if max(str(k*k)) == "5": alst.append(k)
      return alst
    print(aupto(1050)) # Michael S. Branicky, May 15 2021

Formula

a(n) = sqrt(A295015(n)), where sqrt = A000196 or A000194 or A003059.

A294996 Numbers n such that the largest digit of n^3 is 6.

Original entry on oeis.org

4, 6, 25, 36, 37, 40, 51, 60, 64, 77, 85, 86, 117, 118, 134, 136, 146, 154, 185, 218, 236, 250, 345, 360, 370, 374, 381, 384, 400, 405, 465, 510, 585, 586, 587, 600, 606, 625, 640, 705, 770, 805, 806, 825, 845, 850, 860, 1011, 1021, 1045, 1046, 1081, 1101, 1124, 1136, 1145, 1146, 1170, 1177, 1180
Offset: 1

Views

Author

M. F. Hasler, Nov 13 2017

Keywords

Comments

For any term a(n), all numbers of the form a(n)*10^k, k >= 0, are in this sequence. We could call "primitive" the terms not of this form, i.e., without trailing '0'.
Includes a*10^k+b for k >= 3 and [a,b] in {[11, 1], [5, 4], [4, 5], [6, 5], [5, 6], [11, 10], [1, 11], [10, 11]}, and 8*10^k+8 for k >= 4. - Robert Israel, Jul 22 2019

Examples

			4 is in the sequence because the largest digit of 4^3 = 64 is 6.
		

Crossrefs

Cf. A295021 (the corresponding cubes); A278937, A294664, A294665, A294997 .. A294999 (same for digit 3, ..., 9); A295006 (same for squares).
Cf. A000578 (the cubes).

Programs

  • PARI
    for(n=1,2e3, vecmax(digits(n^3))==6&&print1(n","))

A295016 Squares whose largest digit is 6.

Original entry on oeis.org

16, 36, 64, 256, 361, 625, 1156, 1600, 2116, 2601, 3136, 3364, 3600, 4356, 4624, 5625, 6241, 6400, 6561, 11236, 11664, 13456, 14161, 14641, 15625, 16641, 20164, 21316, 24336, 25600, 26244, 30625, 36100, 41616, 42436, 43264, 46225, 46656, 50625, 53361, 56644, 60025, 60516, 61504
Offset: 1

Views

Author

M. F. Hasler, Nov 12 2017

Keywords

Crossrefs

Cf. A295006 (square roots of the terms); A277946, A277947, A277948, A295015 .. A295019 (analog for digits 2 through 9), A295021 (analog for cubes).
Cf. A000290 (the squares).

Programs

  • Mathematica
    Select[Range[250]^2,Max[IntegerDigits[#]]==6&] (* Harvey P. Dale, Jun 14 2025 *)
  • PARI
    is_A295016(n)=issquare(n)&&n&&vecmax(digits(n))==6 \\ The "n&&" avoids an error message for n = 0.

Formula

a(n) = A295006(n)^2.
Showing 1-3 of 3 results.