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 10 results.

A242347 Number of decimal digits of A008559.

Original entry on oeis.org

1, 2, 4, 10, 31, 100, 330, 1093, 3628, 12049, 40023, 132951, 441651, 1467130, 4873698, 16190071, 53782249, 178660761, 593498199, 1971558339
Offset: 1

Views

Author

J. Lowell, May 11 2014

Keywords

Comments

a(n+1)/a(n) is approximately log_2(10) = A020862. - André Engels, Apr 01 2021

Examples

			a(3) = 4 because 1010 has 4 decimal digits.

Links

Crossrefs

Cf. A008559, A055642, A020862.

Programs

  • PARI
    a242347(n) = {my (k=2, d=digits); while(n--, k=fromdigits(d(k,2))); #d(k)} \\ Hugo Pfoertner, Nov 04 2022
  • Python
    A242347_list, l = [1], 2
for _ in range(10):
    l = int(bin(l)[2:])
    A242347_list.append(len(str(l))) # Chai Wah Wu, Dec 26 2014

Formula

a(n) = A055642(A008559(n)). - Michel Marcus, May 11 2014

Extensions

a(1), a(18)-a(20) from Chai Wah Wu, Dec 26 2014

A006938 Convert the last term from decimal to binary! a(1)=3.

Original entry on oeis.org

3, 11, 1011, 1111110011, 1000010001110100011000101111011
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Comments

The next term (a(6)) has 100 digits. - Harvey P. Dale, Feb 28 2012
The number of digits of a(n) are 1, 2, 4, 10, 31, 100, 330, 1093, 3628, 12049, 40023, 132951, 441651, 1467130, 4873698, 16190071, 53782249, 178660761, ... - Robert G. Wilson v, Jul 10 2013
log(a(n))/log(a(n-1)) ~ log_2(10) = A020862. - Robert G. Wilson v, Jul 10 2013

References

  • C. Pickover, Mazes for the Mind, St. Martin's Press, NY, 1992, p. 350.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

For initial terms 2 through 12 see A008559, A006938, A260025, A260024, A260026, A260027, A260028, A260029, A008559 (again), A006938 (again), A260030 respectively.

Programs

  • Mathematica
    NestList[FromDigits[IntegerDigits[#,2]]&,3,4] (* Harvey P. Dale, Feb 28 2012 *)
  • PARI
    lista(nn) = my(k=3); print1(k); for(n=2, nn, print1(", ", k=fromdigits(binary(k)))); \\ Jinyuan Wang, Jan 18 2025
  • Python
    def agen(an):
  while True: yield an; an = int(bin(an)[2:])
g = agen(3)
print([next(g) for i in range(5)]) # Michael S. Branicky, Mar 11 2021

Extensions

a(1)=3 added by N. J. A. Sloane, Jul 14 2015

A260024 Convert the last term from decimal to binary! a(1)=5.

Original entry on oeis.org

5, 101, 1100101, 100001100100101000101, 1010110101111001011010001101011011001100110110011001100101110100101
Offset: 1

Views

Author

N. J. A. Sloane, Jul 14 2015

Keywords

References

  • C. Pickover, Mazes for the Mind, St. Martin's Press, NY, 1992, p. 350.

Crossrefs

For initial terms 2 through 12 see A008559, A006938, A260025, A260024, A260026, A260027, A260028, A260029, A008559 (again), A006938 (again), A260030 respectively.

Programs

  • Mathematica
    NestList[FromDigits[IntegerDigits[#,2]]&,5,5] (* Harvey P. Dale, Jun 23 2025 *)

A260025 Convert the last term from decimal to binary! a(1)=4.

Original entry on oeis.org

4, 100, 1100100, 100001100100101000100, 1010110101111001011010001101011011001100110110011001100101110100100
Offset: 1

Views

Author

N. J. A. Sloane, Jul 14 2015

Keywords

Crossrefs

For initial terms 2 through 12 see A008559, A006938, A260025, A260024, A260026, A260027, A260028, A260029, A008559 (again), A006938 (again), A260030 respectively.

Programs

  • Mathematica
    NestList[FromDigits[IntegerDigits[#,2]]&,4,5] (* Harvey P. Dale, Jun 11 2017 *)
  • PARI
    a(n) = my(k=4); for(i=2, n, k=fromdigits(binary(k))); k; \\ Jinyuan Wang, Jan 18 2025

A260026 Convert the last term from decimal to binary! a(1)=6.

Original entry on oeis.org

6, 110, 1101110, 100001100110100110110, 1010110101111001011010001101011100010111010110010110001101100011110
Offset: 1

Views

Author

N. J. A. Sloane, Jul 14 2015

Keywords

Crossrefs

For initial terms 2 through 12 see A008559, A006938, A260025, A260024, A260026, A260027, A260028, A260029, A008559 (again), A006938 (again), A260030 respectively.

Programs

  • PARI
    a(n) = my(k=6); for(i=2, n, k=fromdigits(binary(k))); k; \\ Jinyuan Wang, Jan 18 2025

A260027 Convert the last term from decimal to binary! a(1)=7.

Original entry on oeis.org

7, 111, 1101111, 100001100110100110111, 1010110101111001011010001101011100010111010110010110001101100011111
Offset: 1

Views

Author

N. J. A. Sloane, Jul 14 2015

Keywords

Crossrefs

For initial terms 2 through 12 see A008559, A006938, A260025, A260024, A260026, A260027, A260028, A260029, A008559 (again), A006938 (again), A260030 respectively.

A260028 Convert the last term from decimal to binary! a(1)=8.

Original entry on oeis.org

8, 1000, 1111101000, 1000010001110100000111001001000
Offset: 1

Views

Author

N. J. A. Sloane, Jul 14 2015

Keywords

Crossrefs

For initial terms 2 through 12 see A008559, A006938, A260025, A260024, A260026, A260027, A260028, A260029, A008559 (again), A006938 (again), A260030 respectively.

Programs

  • PARI
    a(n) = my(k=8); for(i=2, n, k=fromdigits(binary(k))); k; \\ Jinyuan Wang, Jan 18 2025

A260029 Convert the last term from decimal to binary! a(1)=9.

Original entry on oeis.org

9, 1001, 1111101001, 1000010001110100000111001001001
Offset: 1

Views

Author

N. J. A. Sloane, Jul 14 2015

Keywords

Crossrefs

For initial terms 2 through 12 see A008559, A006938, A260025, A260024, A260026, A260027, A260028, A260029, A008559 (again), A006938 (again), A260030 respectively.

A260030 Convert the last term from decimal to binary! a(1)=12.

Original entry on oeis.org

12, 1100, 10001001100, 1001010100000110110010101010001100
Offset: 1

Views

Author

N. J. A. Sloane, Jul 14 2015

Keywords

Comments

The next term has 110 digits. - Harvey P. Dale, May 15 2018

Crossrefs

For initial terms 2 through 12 see A008559, A006938, A260025, A260024, A260026, A260027, A260028, A260029, A008559 (again), A006938 (again), A260030 respectively.

Programs

  • Mathematica
    NestList[FromDigits[IntegerDigits[#,2]]&,12,4] (* Harvey P. Dale, May 15 2018 *)

A006937 Convert the last term from decimal to binary! a(1)=10.

Original entry on oeis.org

10, 1010, 1111110010, 1000010001110100011000101111010, 1100100111110011010011100010101000011000101001000100011011011010001111011100010000001000010011100010
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Comments

The next term, a(6), has 330 digits. - Harvey P. Dale, Aug 10 2011

References

  • C. Pickover, Mazes for the Mind, St. Martin's Press, NY, 1992, p. 350.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Essentially the same as A008559.

Programs

  • Mathematica
    NestList[FromDigits[IntegerDigits[#,2]]&,10,5] (* Harvey P. Dale, Aug 10 2011 *)
Showing 1-10 of 10 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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