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 1-9 of 9 results.

A043681 When cubed gives number composed just of the digits 0, 1, 2, 3.

Original entry on oeis.org

0, 1, 10, 11, 100, 101, 110, 1000, 1001, 1010, 1100, 10000, 10001, 10010, 10100, 11000, 100000, 100001, 100010, 100100, 101000, 110000, 684917, 1000000, 1000001, 1000010, 1000100, 1001000, 1010000, 1100000, 6849170, 10000000, 10000001, 10000010, 10000100, 10001000
Offset: 1

Views

Author

Robert G. Wilson v, Jun 23 2001

Keywords

Comments

684917*10^x (whose cube is 321302302131323213*10^3x) so far is the only entry not of the form 10^a + 10^b, a>b or simply 10^a.

Crossrefs

Cf. A030175.

Programs

  • Mathematica
    Do[ If[ Union[ IntegerDigits[n^3]] [[ -1]] < 4, Print[n] ], {n, 0, 10^8} ]

Extensions

Offset corrected and terms a(33) and beyond added by Giovanni Resta, Mar 14 2020

A196516 Decimal expansion of the number x satisfying x*e^x=3.

Original entry on oeis.org

1, 0, 4, 9, 9, 0, 8, 8, 9, 4, 9, 6, 4, 0, 3, 9, 9, 5, 9, 9, 8, 8, 6, 9, 7, 0, 7, 0, 5, 5, 2, 8, 9, 7, 9, 0, 4, 5, 8, 9, 4, 6, 6, 9, 4, 3, 7, 0, 6, 3, 4, 1, 4, 5, 2, 9, 3, 2, 8, 7, 1, 5, 8, 3, 3, 1, 6, 6, 4, 9, 0, 5, 0, 4, 4, 4, 4, 4, 2, 9, 5, 7, 8, 8, 5, 6, 7, 8, 6, 6, 6, 8, 2, 2, 4, 3, 4, 6, 7, 4
Offset: 1

Views

Author

Clark Kimberling, Oct 03 2011

Keywords

Examples

			1.049908894964039959988697070552897904589...
		

Programs

  • Mathematica
    Plot[{E^x, 1/x, 2/x, 3/x, 4/x}, {x, 0, 2}]
    t = x /. FindRoot[E^x == 1/x, {x, 0.5, 1}, WorkingPrecision -> 100]
    RealDigits[t]  (* A030175 *)
    t = x /. FindRoot[E^x == 2/x, {x, 0.5, 1}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196515 *)
    t = x /. FindRoot[E^x == 3/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196516 *)
    t = x /. FindRoot[E^x == 4/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196517 *)
    t = x /. FindRoot[E^x == 5/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196518 *)
    t = x /. FindRoot[E^x == 6/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196519 *)
    RealDigits[LambertW[3], 10, 50][[1]] (* _G. C. Greubel-, Nov 16 2017 *)
  • PARI
    lambertw(3) \\ G. C. Greubel, Nov 16 2017

A196517 Decimal expansion of the number x satisfying x*e^x=4.

Original entry on oeis.org

1, 2, 0, 2, 1, 6, 7, 8, 7, 3, 1, 9, 7, 0, 4, 2, 9, 3, 9, 2, 1, 2, 0, 7, 4, 1, 6, 5, 4, 9, 5, 1, 5, 3, 4, 4, 7, 5, 0, 1, 5, 1, 2, 5, 2, 1, 8, 2, 9, 6, 2, 5, 9, 8, 1, 7, 3, 9, 2, 0, 3, 5, 9, 0, 7, 0, 0, 6, 3, 4, 1, 3, 2, 9, 8, 1, 7, 7, 2, 6, 7, 7, 2, 2, 7, 8, 2, 6, 1, 0, 4, 9, 7, 6, 5, 6, 8, 3, 7, 7
Offset: 1

Views

Author

Clark Kimberling, Oct 03 2011

Keywords

Examples

			1.2021678731970429392120741654951534475015125218296259...
		

Programs

  • Mathematica
    Plot[{E^x, 1/x, 2/x, 3/x, 4/x}, {x, 0, 2}]
    t = x /. FindRoot[E^x == 1/x, {x, 0.5, 1}, WorkingPrecision -> 100]
    RealDigits[t]  (* A030175 *)
    t = x /. FindRoot[E^x == 2/x, {x, 0.5, 1}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196515 *)
    t = x /. FindRoot[E^x == 3/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196516 *)
    t = x /. FindRoot[E^x == 4/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196517 *)
    t = x /. FindRoot[E^x == 5/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196518 *)
    t = x /. FindRoot[E^x == 6/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196519 *)
    RealDigits[LambertW[4], 10, 50][[1]] (* G. C. Greubel, Nov 16 2017 *)
  • PARI
    lambertw(4) \\ G. C. Greubel, Nov 16 2017

A196518 Decimal expansion of the number x satisfying x*e^x=5.

Original entry on oeis.org

1, 3, 2, 6, 7, 2, 4, 6, 6, 5, 2, 4, 2, 2, 0, 0, 2, 2, 3, 6, 3, 5, 0, 9, 9, 2, 9, 7, 7, 5, 8, 0, 7, 9, 6, 6, 0, 1, 2, 8, 7, 9, 3, 5, 5, 4, 6, 3, 8, 0, 4, 7, 4, 7, 9, 7, 8, 9, 2, 9, 0, 3, 9, 3, 0, 2, 5, 3, 4, 2, 6, 7, 9, 9, 2, 0, 5, 3, 6, 2, 2, 6, 7, 7, 4, 4, 6, 9, 9, 1, 6, 6, 0, 8, 4, 2, 6, 7, 8, 9
Offset: 1

Views

Author

Clark Kimberling, Oct 03 2011

Keywords

Examples

			1.32672466524220022363509929775807966012...
		

Programs

  • Mathematica
    Plot[{E^x, 1/x, 2/x, 3/x, 4/x}, {x, 0, 2}]
    t = x /. FindRoot[E^x == 1/x, {x, 0.5, 1}, WorkingPrecision -> 100]
    RealDigits[t]  (* A030175 *)
    t = x /. FindRoot[E^x == 2/x, {x, 0.5, 1}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196515 *)
    t = x /. FindRoot[E^x == 3/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196516 *)
    t = x /. FindRoot[E^x == 4/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196517 *)
    t = x /. FindRoot[E^x == 5/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196518 *)
    t = x /. FindRoot[E^x == 6/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196519 *)
    RealDigits[LambertW[5], 10, 50][[1]] (* G. C. Greubel, Nov 16 2017 *)
  • PARI
    lambertw(5) \\ G. C. Greubel, Nov 16 2017

A196519 Decimal expansion of the number x satisfying x*e^x=6.

Original entry on oeis.org

1, 4, 3, 2, 4, 0, 4, 7, 7, 5, 8, 9, 8, 3, 0, 0, 3, 1, 1, 2, 3, 4, 0, 7, 8, 0, 0, 7, 2, 1, 2, 0, 5, 8, 6, 9, 4, 7, 8, 6, 4, 3, 4, 6, 0, 8, 8, 0, 4, 3, 0, 2, 0, 2, 5, 6, 5, 5, 9, 4, 8, 4, 9, 6, 3, 4, 3, 3, 9, 9, 5, 9, 3, 2, 5, 9, 8, 3, 1, 1, 1, 6, 8, 5, 7, 6, 3, 8, 4, 2, 2, 2, 9, 9, 4, 4, 5, 6, 5, 1
Offset: 1

Views

Author

Clark Kimberling, Oct 03 2011

Keywords

Examples

			1.43240477589830031123407800721205869478643460...
		

Programs

  • Mathematica
    Plot[{E^x, 1/x, 2/x, 3/x, 4/x}, {x, 0, 2}]
    t = x /. FindRoot[E^x == 1/x, {x, 0.5, 1}, WorkingPrecision -> 100]
    RealDigits[t]  (* A030175 *)
    t = x /. FindRoot[E^x == 2/x, {x, 0.5, 1}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196515 *)
    t = x /. FindRoot[E^x == 3/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196516 *)
    t = x /. FindRoot[E^x == 4/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196517 *)
    t = x /. FindRoot[E^x == 5/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196518 *)
    t = x /. FindRoot[E^x == 6/x, {x, 0.5, 2}, WorkingPrecision -> 100]
    RealDigits[t]  (* A196519 *)
    RealDigits[LambertW[6], 10, 50][[1]] (* G. C. Greubel, Nov 16 2017 *)
  • PARI
    lambertw(6) \\ G. C. Greubel, Nov 16 2017

Extensions

Terms a(95) onward corrected by G. C. Greubel, Nov 16 2017

A030174 Squares composed of digits {1,2,3}.

Original entry on oeis.org

1, 121, 12321, 1322122321, 132233322321, 213223221121, 13223121322321, 1212111311221321, 131332121232312121, 31121322221111133211321, 3322133322121313132333322321, 12232213113321121113332133323121, 3231221313313311221231322223122312333121, 311323333121312322332133323111223321313321
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A030175.

Formula

a(n) = A030175(n)^2. - Elmo R. Oliveira, Jul 17 2025

Extensions

More terms from Patrick De Geest, Mar 15 2000.
More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 14 2005
a(13)-a(14) from Mishima's website added by Elmo R. Oliveira, Jul 17 2025

A031997 Odd numbers which when cubed give number composed just of the digits 0, 1, 2, 3.

Original entry on oeis.org

1, 11, 101, 1001, 10001, 100001, 684917, 1000001, 10000001, 100000001, 1000000001, 10000000001, 100000000001, 1000000000001, 10000000000001, 100000000000001, 1000000000000001, 10000000000000001, 100000000000000001, 1000000000000000001
Offset: 1

Views

Author

Robert G. Wilson v, Jun 23 2001

Keywords

Comments

Note that 684917 (whose cube is 321302302131323213) so far is the only entry not of the form 10^x + 1.

Crossrefs

Programs

  • Mathematica
    Do[ If[ Union[ IntegerDigits[ n^3 ] ] [ [ -1 ] ] < 4, Print[ n ] ], {n, 1, 10^9, 2} ] (* corrected by Friedjof Tellkamp, Apr 24 2025 *)
    (* faster code *)
    DigitsLEQ3[n_] := And @@ (LessEqual[#, 3] & /@ IntegerDigits[n])
    Arr = {1, 7}; For[i = 1, i < 10, i++, Arr = Flatten[Table[Select[Arr + 10^i j, DigitsLEQ3[Mod[#^3, 10^(i+1)]] &], {j, 0, 9}]]];
    Select[Arr, DigitsLEQ3[#^3] &] (* Friedjof Tellkamp, Apr 25 2025 *)
  • Python
    A031997_list = [n for n in range(1,10**6,2) if max(str(n**3)) <= '3'] # Chai Wah Wu, Feb 23 2016

Extensions

Term 0 removed and a(12)-a(17) added by Chai Wah Wu, Feb 25 2016
a(18)-a(20) from Giovanni Resta, Mar 14 2020

A136812 Numbers k such that k and k^2 use only the digits 0, 1, 2, 3 and 6.

Original entry on oeis.org

0, 1, 6, 10, 11, 60, 100, 101, 106, 110, 111, 361, 600, 601, 1000, 1001, 1006, 1010, 1011, 1060, 1100, 1101, 1106, 1110, 1631, 3606, 3610, 6000, 6001, 6010, 6011, 10000, 10001, 10006, 10010, 10011, 10060, 10100, 10101, 10106, 10110, 10111, 10301, 10306, 10600, 11000, 11001, 11006, 11010, 11060, 11100, 11101, 16310, 32111, 36060, 36100, 36361
Offset: 1

Views

Author

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

Keywords

Comments

Generated with DrScheme.

Examples

			1031316261^2 = 1063613230203020121.
		

Crossrefs

Cf. A136808, ..., A137147.

A294660 Least nonnegative integer not occurring earlier whose square has no digit in common with the square of the previous term, a(0) = 0.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 9, 8, 10, 15, 12, 16, 20, 11, 22, 13, 18, 14, 28, 19, 17, 21, 23, 26, 29, 24, 30, 25, 33, 58, 27, 34, 47, 38, 45, 31, 48, 41, 50, 37, 52, 44, 65, 40, 57, 76, 32, 63, 35, 60, 39, 62, 36, 88, 46, 67, 51, 183, 75, 43, 55, 42, 53, 56, 70, 61, 64, 85, 59, 77, 69, 73, 78, 89
Offset: 0

Views

Author

M. F. Hasler, Nov 08 2017

Keywords

Comments

This is not a permutation of the nonnegative integers, since numbers whose square has all digits '1' through '9' (cf. A294661, e.g., 11826 with 11826^2 = 139854276) can never appear - and these numbers have asymptotic density 1.
Will all integers whose square does not have all of the digits 1-9, eventually appear? Or might the sequence be finite? Since a(n)^2 has no digits in common with a(n-1)^2, it is sufficient for a(n+1) to exist, to find a number whose square has a subset of the digits of a(n-1)^2. Is this always possible? This problem sometimes has only "sporadic k-digital solutions", see, e.g., A058430, A030175, ... and the link to De Geest's page.

Examples

			Since a(7)^2 = 7^2 = 49, the subsequent term cannot be 8, since 8^2 = 64 has the digit 4 in common with 49. Therefore, a(8) = 9, with 9^2 = 81 having no common digit with 49.
a(1201) = 1037. So the square of the next term must not have any of the digits in {0, 1, 3, 5, 6, 7, 9}, only 2, 4, 8 are allowed. The least such number that has not been used before is a(1202) = 210912978, with a(1202)^2 = 210912978^2 = 44484284288828484. - _Alois P. Heinz_, Nov 09 2017
		

Crossrefs

Cf. A030287 (strictly increasing), A067581 (do not take squares).

Programs

  • PARI
    {u=a=0; for(n=0, 99, print1(a", "); u+=1<
    				
  • PARI
    {u=[a=0]; for(n=0, 99, print1(a", "); D=Set(if(a, digits(a^2))); for(k=u[1]+1, oo, setsearch(u, k)&&next; #setintersect(D, Set(digits(k^2)))&&next; u=setunion(u,[a=k]); break); while(#u>1&&u[2]==u[1]+1,u=u[^1])); a}
Showing 1-9 of 9 results.