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 1-10 of 12 results. Next

A277959 Numbers k such that 2 is the largest decimal digit of k^2.

Original entry on oeis.org

11, 101, 110, 149, 1001, 1010, 1011, 1100, 1101, 1490, 10001, 10010, 10011, 10100, 10110, 11000, 11001, 11010, 14499, 14900, 100001, 100010, 100011, 100100, 100101, 100110, 101000, 101001, 101100, 110000, 110001, 110010, 110100, 144990, 149000, 316261
Offset: 1

Views

Author

Colin Barker, Nov 06 2016

Keywords

Comments

The terms > 1 of A058411 can be considered as primitive elements of this sequence, obtained by multiplying those by powers of 10 (cf. formula). These terms of A058411 have at least 2 nonzero digits, and therefore their square has at least one digit 2. - M. F. Hasler, Nov 15 2017

Crossrefs

Cf. A277946 (the squares); A277960, A277961, A295005, ..., A295009 (analog for largest digit 3, 4, 5, ..., 9).
Cf. A058411, A058412 and A058413, ..., A058474. (Similar but no trailing 0's allowed.)
Cf. A136808 and A136809, ..., A137147 for other digit combinations. (Numbers must satisfy the same restriction as their squares.)

Programs

  • Mathematica
    Select[Range[4*10^5], And[#[[2]] > 0, Union@ Take[RotateLeft[#, 2], 7] == {0}] &@ DigitCount[#^2] &] (* Michael De Vlieger, Nov 16 2017 *)
  • PARI
    L=List(); for(n=1, 10000, if(vecmax(digits(n^2))==2, listput(L, n))); Vec(L)
    
  • PARI
    A277959(LIM=1e15, L=List(), N=1)={while(LIM>N=next_A058411(N),my(t=N); until(LIMM. F. Hasler, Nov 15 2017

Formula

Equals (A058411 \ {1})*A011557, where A011557 = { 10^k; k >= 0 }. - M. F. Hasler, Nov 16 2017

Extensions

Edited by M. F. Hasler, Nov 16 2017

A137147 Numbers k such that k and k^2 use only the digits 5, 6, 7, 8 and 9.

Original entry on oeis.org

76, 87, 766, 887, 7666, 8887, 9786, 76587, 76666, 87576, 759576, 766666, 869866, 869867, 886886, 888587, 988866, 7666666, 8766867, 8885887, 76587576, 76666666, 76789686, 86998666, 87565786, 87685676, 88766867, 97759786, 97957576, 766666666, 875765766, 886885887, 887579686, 977699687
Offset: 1

Views

Author

Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008

Keywords

Comments

Generated with DrScheme.

Examples

			989878759589576^2 = 979859958686597599779967859776.
		

Crossrefs

Cf. A136808, A136809, ..., A137146 for other digit combinations.
Cf. A000290 (the squares); A027675, A058411, ..., A058474 (3-digit combinations).
Cf. A277959, A277960, A277961, A295005, ..., A295009 (squares with largest digit = 2, 3, 4, 5, ..., 9).

A277948 Squares whose largest decimal digit is 4.

Original entry on oeis.org

4, 144, 324, 400, 441, 1024, 1444, 2304, 2401, 10404, 14400, 23104, 32041, 32400, 33124, 40000, 40401, 44100, 101124, 102400, 103041, 110224, 114244, 121104, 131044, 144400, 203401, 204304, 213444, 230400, 232324, 240100, 300304, 301401, 421201, 1004004
Offset: 1

Views

Author

Colin Barker, Nov 05 2016

Keywords

Comments

A subsequence of A158082, in turn a subsequence of A000290.

Crossrefs

Cf. A000290 (the squares).
Cf. A277961 (square roots of these terms).
Cf. A277946, A277947, A295015, ..., A295019 (analog for largest digit = 2, 3, 5, ..., 9).
Cf. A058412, A058411, ..., A058474 and A136808, A136809, ..., A137147 for other restrictions on digits of squares.

Programs

  • Magma
    [n^2: n in [1..1000000] | Maximum(Intseq(n^2)) eq 4]; // Vincenzo Librandi, Nov 06 2016
  • Mathematica
    Select[Range[1100]^2,Max[IntegerDigits[#]]==4&] (* Harvey P. Dale, Jul 01 2017 *)
  • PARI
    L=List(); for(n=1, 10000, if(vecmax(digits(n^2))==4, listput(L, n^2))); Vec(L)
    

Formula

a(n) = A277961(n)^2. - M. F. Hasler, Nov 12 2017
Intersection of A000290 and A277966. - M. F. Hasler, Nov 15 2017

A277960 Numbers n such that 3 is the largest decimal digit of n^2.

Original entry on oeis.org

111, 351, 361, 1110, 1149, 1761, 3510, 3610, 10101, 10111, 10149, 11100, 11101, 11490, 17610, 35100, 36100, 36361, 36501, 45861, 100111, 100649, 101010, 101011, 101110, 101149, 101490, 110101, 111000, 111001, 111010, 114111, 114499, 114900, 176100, 176361
Offset: 1

Views

Author

Colin Barker, Nov 06 2016

Keywords

Crossrefs

Programs

  • PARI
    L=List(); for(n=1, 10000, if(vecmax(digits(n^2))==3, listput(L, n))); Vec(L)

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.

A295009 Numbers k such that the largest digit of k^2 is 9.

Original entry on oeis.org

3, 7, 13, 14, 17, 23, 27, 30, 31, 33, 36, 37, 43, 44, 47, 53, 54, 57, 63, 64, 67, 70, 73, 77, 83, 86, 87, 89, 93, 95, 96, 97, 98, 99, 103, 107, 113, 114, 117, 118, 123, 127, 130, 133, 134, 136, 137, 138, 139, 140, 141, 143, 147, 148, 153, 157, 158, 161, 163, 164, 167, 170, 171
Offset: 1

Views

Author

M. F. Hasler, Nov 12 2017

Keywords

Examples

			23 is in this sequence because 23^2 = 529 has 9 as largest digit.
		

Crossrefs

Cf. A295019 (the corresponding squares), A277959 .. A277961 (same for digit 2 .. 4), A295005 .. A295008 (same for digit 5 .. 8).
Cf. A000290 (the squares).

Programs

  • PARI
    select( is_A295009(n)=n&&vecmax(digits(n^2))==9 , [0..999]) \\ The "n&&" avoids an error message for n=0.

Formula

a(n) = sqrt(A295019(n)), where sqrt = A000196 or A000194 or A003059.

A294663 Cubes whose largest digit is 4.

Original entry on oeis.org

343, 314432, 343000, 34012224, 314432000, 343000000, 34012224000, 314432000000, 343000000000, 442102433032, 30304210142233, 34012224000000, 143121324002112, 314432000000000, 333014302331144, 343000000000000, 442102433032000, 30304210142233000, 34012224000000000
Offset: 1

Views

Author

M. F. Hasler, Nov 12 2017

Keywords

Comments

For any term a(n), all numbers of the form a(n)*10^3k, k >= 0, are in this sequence. Primitive terms, i.e., not of this form (or equivalently: without trailing '0'), are 343, 314432, 34012224, 442102433032, 30304210142233, 143121324002112, 333014302331144, ...

Examples

			343 is in the sequence because it is a cube, 343 = 7^3, and its largest digit is 4.
		

Crossrefs

Cf. A294664 (the corresponding cubic roots).
Cf. A277948 = A277961^2 (analog for squares).
Cf. A278936, A295025, A295021, ..., A295024 (analog for digits 3, 5, 6, ..., 9).
Cf. A000578 (the cubes).

Programs

  • PARI
    for(n=1,2e8, vecmax(digits(n^3))==4&&print1(n^3,","))

Formula

a(n) = A294664(n)^3.

A294664 Numbers n such that the largest digit of n^3 is 4.

Original entry on oeis.org

7, 68, 70, 324, 680, 700, 3240, 6800, 7000, 7618, 31177, 32400, 52308, 68000, 69314, 70000, 76180, 311770, 324000, 353068, 523080, 680000, 693140, 700000, 756658, 761800, 1039247, 2715974, 2732441, 3117700, 3240000, 3511617, 3530680, 4689368, 5230800, 6800000, 6931400, 7000000
Offset: 1

Views

Author

M. F. Hasler, Nov 12 2017

Keywords

Comments

For any term a(n), all numbers of the form a(n)*10^k, k >= 0, are in this sequence. Primitive terms, i.e., not of this form (or equivalently: without trailing '0'), are 7, 68, 324, 7618, 31177, 52308, 69314, 353068, 756658, 1039247, 2715974, 2732441, 3511617, 4689368, 7571814, 12811968, 15904541, ...
All terms have last nonzero digit 1, 4, 7 or 8 and leading digit <= 7. - Robert Israel, Nov 13 2017
The number formed by the first m digits of a term is always less than c*10^m with c = (4/9)^(1/3) = .7631428283688879... - M. F. Hasler, Nov 13 2017

Examples

			7 is in the sequence because the largest digit of 7^3 = 343 is 4.
		

Crossrefs

Cf. A294663 (the corresponding cubes), A278937, A294665, A294996 - A294999 (analog for digits 3, 5, 6 - 9); A277961 (analog for squares).
Cf. A000578 (the cubes).

Programs

  • Maple
    select(n -> max(convert(n^3,base,10))=4, [$1..10^6]); # Robert Israel, Nov 13 2017
  • PARI
    for(n=1,2e8, vecmax(digits(n^3))==4&&print1(n","))

A295006 Numbers n such that the largest digit of n^2 is 6.

Original entry on oeis.org

4, 6, 8, 16, 19, 25, 34, 40, 46, 51, 56, 58, 60, 66, 68, 75, 79, 80, 81, 106, 108, 116, 119, 121, 125, 129, 142, 146, 156, 160, 162, 175, 190, 204, 206, 208, 215, 216, 225, 231, 238, 245, 246, 248, 249, 250, 251, 252, 254, 255, 256, 258, 325, 334, 340, 354, 355, 369, 375, 379
Offset: 1

Views

Author

M. F. Hasler, Nov 12 2017

Keywords

Examples

			19 is in this sequence because 19^2 = 361 has 6 as largest digit.
		

Crossrefs

Cf. A295016 (the corresponding squares), A277959, A277960, A277961, A295005 .. A295009 (analog for digits 2 through 9), A294996 (analog for cubes).
Cf. A000290 (the squares).

Programs

  • Mathematica
    Select[Range[400],Max[IntegerDigits[#^2]]==6&] (* Harvey P. Dale, Mar 30 2024 *)
  • PARI
    select( is_A295006(n)=n&&vecmax(digits(n^2))==6 , [0..999]) \\ The "n&&" avoids an error message for n=0.

Formula

a(n) = sqrt(A295016(n)), where sqrt = A000196 or A000194 or A003059.

A295008 Numbers whose square has largest digit 8.

Original entry on oeis.org

9, 22, 28, 29, 41, 59, 62, 72, 78, 90, 91, 92, 94, 104, 109, 122, 126, 128, 135, 151, 159, 168, 169, 178, 184, 191, 192, 195, 196, 202, 209, 220, 221, 232, 241, 242, 259, 261, 262, 268, 278, 279, 280, 284, 285, 289, 290, 291, 292, 294, 295, 296, 298, 322, 328, 329, 341, 344, 349
Offset: 1

Views

Author

M. F. Hasler, Nov 12 2017

Keywords

Comments

Includes a*10^n+b for n >= 2 and [a,b] in {[4, 1], [9, 1], [2, 2], [9, 2], [1, 4], [6, 4], [9, 4], [8, 5], [4, 6], [9, 6], [5, 8], [8, 8], [9, 8], [1, 9], [2, 9], [4, 9], [6, 9], [8, 9], [9, 9]}. - Robert Israel, Nov 13 2017

Examples

			28 is in this sequence because 28^2 = 784 has 8 as largest digit.
		

Crossrefs

Cf. A295018 (the corresponding squares), A277959 .. A277961 (same for digit 2 .. 4), A295005 .. A295009 (same for digit 5 .. 9).
Cf. A000290 (the squares).

Programs

  • Maple
    select(t -> max(convert(t^2,base,10))=8, [$1..1000]); # Robert Israel, Nov 13 2017
  • Mathematica
    Select[Range[400],Max[IntegerDigits[#^2]]==8&] (* Harvey P. Dale, Jun 02 2019 *)
  • PARI
    select( is_A295008(n)=n&&vecmax(digits(n^2))==8 , [0..999]) \\ The "n&&" avoids an error message for n=0.
    
  • Python
    def ok(n): return max(int(d) for d in str(n*n)) == 8
    print(list(filter(ok, range(350)))) # Michael S. Branicky, Sep 22 2021

Formula

a(n) = sqrt(A295018(n)), where sqrt = A000196 or A000194 or A003059.
Showing 1-10 of 12 results. Next