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 1-8 of 8 results.

A014569 Super-3 Numbers (3n^3 contains substring '333' in its decimal expansion).

Original entry on oeis.org

261, 462, 471, 481, 558, 753, 1036, 1046, 1471, 1645, 1752, 1848, 1923, 1926, 1968, 2031, 2231, 2232, 2363, 2395, 2471, 2591, 2610, 3058, 3087, 3148, 3163, 3172, 3181, 3471, 3494, 3542, 3851, 3884, 4143, 4269, 4314, 4471, 4527, 4554, 4620, 4710, 4732
Offset: 1

Views

Author

Keywords

Comments

For any term a(n), all numbers a(n)*10^k, k >= 0, are also in the sequence. More interestingly, all numbers N == 471 (mod 1000) are in the sequence, since 471^3*3 == 333 (mod 1000). - M. F. Hasler, Jul 16 2024
Conjecture: a(n) ~ n. - Charles R Greathouse IV, Dec 04 2024

Examples

			1752 is in the sequence since 3 * 1752^3 = 161'333'13024.
		

References

  • C. A. Pickover, Keys to Infinity. New York: Wiley, p. 7, 1995.

Crossrefs

Cf. A032743-A032749 (similar for d=2, ..., 9).

Programs

  • Mathematica
    Select[Range[5000],MemberQ[Partition[IntegerDigits[3#^3],3,1],{3,3,3}]&] (* Harvey P. Dale, Feb 01 2013 *)
  • PARI
    select( {is_A014569(n, d=3, m=10^d, r=m\9*d)=n=d*n^d; until(r>n\=10, n%m==r && return(1))}, [0..4999]) \\ Using the (optional) 2nd arg d=2..9 allows to compute the sequences A032743-A032749. - M. F. Hasler, Jul 16 2024
    
  • Python
    is_A014569=lambda n, d=3: str(d)*d in str(d*n**d) # M. F. Hasler, Jul 16 2024

Formula

n < a(n) < 200n for n > 2. - Charles R Greathouse IV, Dec 04 2024

Extensions

Corrected and extended by Patrick De Geest, May 15 1998
Offset changed to 1 by M. F. Hasler, Jul 16 2024

A032743 Super-2 Numbers (2 * n^2 contains substring '22' in its decimal expansion).

Original entry on oeis.org

19, 31, 69, 81, 105, 106, 107, 119, 127, 131, 169, 181, 190, 219, 231, 247, 269, 281, 310, 318, 319, 331, 332, 333, 334, 335, 336, 337, 338, 339, 348, 369, 381, 419, 431, 454, 469, 481, 511, 519, 531, 558, 569, 581, 601, 619, 631, 669, 679, 681, 690, 715
Offset: 1

Views

Author

Patrick De Geest, May 15 1998

Keywords

Comments

For any term a(n), all numbers a(n)*10^k, k >= 0, are also in the sequence. Moreover, the first four terms satisfy 2*a(n)^2 == 22 (mod 100), therefore any number ending in 19, 31, 69 or 81 (possibly followed by trailing '0's) is in the sequence. - M. F. Hasler, Jul 16 2024
Conjecture: a(n) ~ n. - Charles R Greathouse IV, Dec 04 2024

References

  • C. A. Pickover, "Keys to Infinity", New York: Wiley, p. 7, 1995.

Crossrefs

Cf. A014569 (similar for d=3), A032744 - A032749 (similar for d=4, ..., 9).

Programs

  • Mathematica
    Select[Range[1000],MemberQ[Partition[IntegerDigits[2#^2],2,1],{2,2}]&] (* Harvey P. Dale, May 09 2012 *)
    Select[Range[750],SequenceCount[IntegerDigits[2#^2],{2,2}]>0&] (* Harvey P. Dale, May 13 2022 *)
  • PARI
    select( {is_A032743(n, d=2, m=10^d, r=m\9*d)=n=d*n^d; until(r>n\=10, n%m==r && return(1))}, [0..999]) \\ M. F. Hasler, Jul 16 2024
    
  • Python
    is_A032743=lambda n, d=2: str(d)*d in str(d*n**d) # M. F. Hasler, Jul 16 2024

A032744 Super-4 Numbers (4 * n^4 contains substring '4444' in its decimal expansion).

Original entry on oeis.org

1168, 4972, 7423, 7752, 8431, 10267, 11317, 11487, 11549, 11680, 16588, 16664, 16837, 18257, 18597, 19784, 19933, 22217, 22504, 22819, 22829, 24078, 24331, 24514, 25296, 25698, 26685, 26738, 27812, 27973, 28988, 32466, 32467, 32735, 34078, 34636, 35248, 36219, 36602
Offset: 1

Views

Author

Patrick De Geest, May 15 1998

Keywords

Comments

a(17) = 19933 and a(20) = 22819 are such that a(n)^4 == 111121 (mod 10^6), therefore any number ending in (0|5)19933 or in (0|5)22819, where (a|b) means a or b, is in the sequence. Of course, for each term a(n), all numbers a(n)*10^k, k >= 0, are also in the sequence. - M. F. Hasler, Jul 16 2024
Conjecture: a(n) ~ n. - Charles R Greathouse IV, Dec 04 2024

References

  • C. A. Pickover, "Keys to Infinity", New York: Wiley, p. 7, 1995.

Crossrefs

Cf. A014569 (d=3), A032743-A032749 (d=2, ..., 9).

Programs

Extensions

Offset changed to 1 by M. F. Hasler, Jul 16 2024

A032745 Super-5 Numbers (5 * n^5 contains substring '55555' in its decimal expansion).

Original entry on oeis.org

4602, 5517, 7539, 12955, 14555, 20137, 20379, 26629, 32767, 35689, 35825, 37706, 46020, 46715, 51988, 55170, 66344, 73338, 73974, 75390, 76157, 86025, 91497, 105852, 114488, 129550, 132234, 145550, 146399, 158651, 160897, 171673, 174782, 176988, 184471, 188421, 191261, 192607
Offset: 1

Views

Author

Patrick De Geest, May 15 1998

Keywords

Comments

The terms a({15, 25, 34}) = {51988, 114488, 176988} are such that 5*a(n)^5 == 55555840 (mod 10^8). Therefore any number congruent to one of these, modulo 5*10^5, is also in the sequence. Of course, for any a(n) in the sequence, any a(n)*10^k, k >= 0, is also in the sequence. - M. F. Hasler, Jul 16 2024
Conjecture: a(n) ~ n. - Charles R Greathouse IV, Dec 04 2024

References

  • C. A. Pickover, "Keys to Infinity", New York: Wiley, p. 7, 1995.

Crossrefs

Programs

  • Maple
    filter:= proc(n) local S;
      StringTools:-Search("55555",sprintf("%d",5*n^5))<> 0
    end proc:
    select(filter, [$1..200000]); # Robert Israel, Jul 14 2025
  • Mathematica
    Select[Range[200000],SequenceCount[IntegerDigits[5#^5],{5,5,5,5,5}]>0&] (* Harvey P. Dale, Jul 16 2016 *)
  • PARI
    select( {is_A032745(n)=is_A032743(n, 5)}, [1..2^18]) \\ M. F. Hasler, Jul 16 2024

Extensions

Offset changed to 1 by Andrew Howroyd, Jul 16 2024

A032746 Super-6 Numbers (6 * n^6 contains substring '666666' in its decimal expansion).

Original entry on oeis.org

27257, 272570, 302693, 323576, 364509, 502785, 513675, 537771, 676657, 678146, 731378, 831122, 836553, 913797, 920456, 921269, 1045361, 1144983, 1169054, 1283069, 1288697, 1292673, 1343642, 1346117, 1472078, 1523993, 1640026
Offset: 1

Views

Author

Patrick De Geest, May 15 1998

Keywords

Comments

The terms a({5, 9, 11, 12}) = {364509, 676657, 731378, 831122} are such that 6*a(n)^6 == 66666646, 66666694, or 66666624 (mod 10^8). Therefore, any number congruent to one of these (mod 5*10^7) is also in the sequence. Of course, for any term a(n), all numbers a(n)*10^k, k >= 0, are also in the sequence. - M. F. Hasler, Jul 16 2024
Conjecture: a(n) ~ n. - Charles R Greathouse IV, Dec 04 2024

References

  • C. A. Pickover, "Keys to Infinity", New York: Wiley, p. 7, 1995.

Crossrefs

Cf. A014569 (d=3), A032743 - A032749 (d=2, ..., 9).

Programs

  • Mathematica
    With[{c=6},Select[Range[165*10^4],SequenceCount[IntegerDigits[c #^c],PadRight[ {},c,c]]>0&]] (* Harvey P. Dale, Jan 18 2023 *)
  • PARI
    select( {is_A032746(n)=is_A014569(n,6)}, [1..10^5])
    for(n=1, oo, is_A032746(n)&& print1(n", ")) \\ Quite slow... - M. F. Hasler, Jul 16 2024

Extensions

Offset changed to 1 by M. F. Hasler, Jul 16 2024

A032748 Super-8 Numbers (8 * n^8 contains substring '88888888' in its decimal expansion).

Original entry on oeis.org

185423, 641519, 1551728, 1854230, 6415190, 12043464, 12147605, 15517280, 16561735, 18542300, 26908132, 29242698, 33491333, 34982204, 35866945, 37584428, 44263715, 45980752, 54555936, 56148739, 60883944, 64151900
Offset: 1

Views

Author

Patrick De Geest, May 15 1998

Keywords

Comments

All numbers congruent to a(2) = 641519 (mod 5*10^10) are also in the sequence. - M. F. Hasler, Jul 17 2024
Conjecture: a(n) ~ n. - Charles R Greathouse IV, Dec 04 2024

References

  • C. A. Pickover, "Keys to Infinity", New York: Wiley, p. 7, 1995.

Crossrefs

Cf. A014569 (similar for d=3), A032743 - A032749 (similar for d=2, ..., 9).

Programs

  • Maple
    d := 8 ;
    for n from 1 do
            convert(d*n^d,base,10) ;
            if verify([8,8,8,8,8,8,8,8],%,'sublist') then
                    print(n) ;
            end if;
    end do: # R. J. Mathar, Jan 11 2013
  • Mathematica
    Select[Range[65*10^6],SequenceCount[IntegerDigits[8*#^8],{8,8,8,8,8,8,8,8}]>0&] (* Harvey P. Dale, Dec 24 2016 *)
  • PARI
    \\ See A014569 (not very efficient for d=8).
    
  • Python
    # See A014569 (not very efficient for d=8).

Extensions

Offset changed to 1 by M. F. Hasler, Jul 17 2024

A032747 Super-7 Numbers (7 * n^7 contains substring '7777777' in its decimal expansion).

Original entry on oeis.org

140997, 490996, 1184321, 1259609, 1409970, 1783166, 1886654, 1977538, 2457756, 2714763, 2750425, 2980991, 3043607, 3283057, 3689639, 4191601, 4258476, 4642725, 4909960, 4973029, 5242829, 5349973, 5444788, 5523544, 5682065
Offset: 1

Views

Author

Patrick De Geest, May 15 1998

Keywords

Comments

The term a(6) = 1783166 is such that 7*a(6)^7 == 777777792 (mod 10^9). Therefore, all numbers congruent to a(6) (mod 5*10^8) are also in the sequence. Of course, for any term a(n), all numbers a(n)*10^k, k >= 0, are also in the sequence. - M. F. Hasler, Jul 16 2024
Conjecture: a(n) ~ n. - Charles R Greathouse IV, Dec 04 2024

References

  • C. A. Pickover, "Keys to Infinity", New York: Wiley, p. 7, 1995.

Crossrefs

Cf. A014569 (d=3), A032743 (d=2) - A032749 (d=9).

Programs

  • Mathematica
    Select[Range[6*10^6],MemberQ[Partition[IntegerDigits[7#^7],7,1],{7,7,7,7,7,7,7}]&] (* Harvey P. Dale, Sep 01 2014 *)
  • PARI
    is_A032747(n)=is_A014569(n, 7)
    for(n=1,oo, is_A032747(n)&& print1(n", ")) \\ Quite slow, even to get the first few terms. - M. F. Hasler, Jul 16 2024

A032757 Palindromic Super-9 Numbers.

Original entry on oeis.org

351636153, 6260330626, 9999999999, 99999999999, 999999999999, 9971824281799, 9999999999999, 59999999999995, 89999999999998, 99999999999999, 499999999999994, 596038242830695, 599999999999995
Offset: 1

Views

Author

Patrick De Geest, May 15 1998; extended Feb 22 2004

Keywords

Comments

The smallest palindromic super-9 prime is 15125111011152151.

References

  • C. A. Pickover, "Keys to Infinity", New York: Wiley, p. 7, 1995.

Crossrefs

Showing 1-8 of 8 results.