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 1-5 of 5 results.

A376185 a(n) = denominator of the sum S(n) defined in A376062.

Original entry on oeis.org

12, 48, 624, 97968, 2399530224, 1439436326371902768, 517994234419759747473589427583418224, 67079506723028253472357256785558488997471406450171845011442457607246768
Offset: 1

Views

Author

N. J. A. Sloane, Sep 15 2024

Keywords

Examples

			The initial values of S(n) are 7/12, 43/48, 619/624, 97963/97968, 2399530219/2399530224, 1439436326371902763/1439436326371902768 ...
		

Crossrefs

Formula

1/a(n) = 1/a(n-1) - 1/(4*A376062(n)) for n >= 2.

A376048 Lexicographically earliest sequence of positive integers a(1), a(2), a(3), ... such that for any n > 0, S(n) = Sum_{k = 1..n} b(k)/a(k) < 1, where {b(k)} = 3,1,4,1,5,... are the digits of Pi (cf. A000796).

Original entry on oeis.org

4, 5, 81, 1621, 13130101, 310319170452181, 21399552788917656689963823241, 1373822578697020375503379392874191898311737749943783762521
Offset: 1

Views

Author

N. J. A. Sloane, Sep 13 2024

Keywords

References

  • Rémy Sigrist and N. J. A. Sloane, Dampening Down a Divergent Series, Manuscript in preparation, September 2024.

Crossrefs

Programs

  • Maple
    For Maple code for all these sequences, see A376056.

Formula

a(n+1) = b(n+1)*A376049(n) + 1.

A376244 Lexicographically earliest sequence of positive integers a(1), a(2), ... with the property that the lexicographically earliest sequence of positive integers b(1), b(2), ... such that for any n > 0, S(n) = Sum_{k = 1..n} 1 / (a(k)*b(k)) < 1, also implies that S(n) is never of the form (e_n - 1) / e_n for some integer e_n.

Original entry on oeis.org

3, 4, 5, 4, 7, 3, 9, 1, 11, 4, 13, 7, 9, 19, 10, 2, 23, 25, 29, 27, 53, 1, 17, 7, 2, 2, 15, 67, 22, 37
Offset: 1

Views

Author

Rémy Sigrist and N. J. A. Sloane, Sep 16 2024

Keywords

Comments

Is this sequence infinite?

Examples

			The initial terms are:
  n  a(n)  b(n)    S(n)
  -  ----  ------  ---------------------------
  1     3       1  1/3
  2     4       1  7/12
  3     5       1  47/60
  4     4       2  109/120
  5     7       2  823/840
  6     3      17  4757/4760
  7     9     177  7582661/7582680
  8     1  399089  3026164178509/3026164178520
		

Crossrefs

Cf. A374663, A376062, A376184, A376245 (corresponding b's), A376246-A376247 (numerator and denominator of corresponding S(n)).

Programs

  • PARI
    \\ See Links section.

A376184 Lexicographically earliest sequence of positive integers a(1), a(2), a(3), ... such that for any n > 0, S(n) = Sum_{k = 1..n} b(k)/a(k) < 1, where {b(k)} is the sequence b(1)=5/4, b(2*i)=3/2, b(2*i+1)=6/5 (i>0).

Original entry on oeis.org

2, 5, 17, 341, 92753, 10753782821, 92515075960384748177, 10698799099944699918936107506299150093941, 91571441744782016867976366392607084634231243149599342901251284090792487979854033
Offset: 1

Views

Author

N. J. A. Sloane, Sep 15 2024

Keywords

Comments

This sequence and A376062 were discovered by Rémy Sigrist on Sep 09 2024. The two sequences {b(1)=7/6, b(k)=5/4 for k>1} and {b(1)=5/4, b(2*k)=3/2, b(2*k+1)=6/5 for k>0} are the first sequences {b(i)} discovered with the property that the sums S(n) do not converge to numbers of the form (e_n - 1)/e_n as n-> oo.

Examples

			The initial values of S(n) are 5/8, 37/40, 677/680, 231877/231880, 21507565637/21507565640, 231287689900961870437/231287689900961870440, ...
		

Crossrefs

A376186 a(n) = denominator of the sum S(n) defined in A376184.

Original entry on oeis.org

8, 40, 680, 231880, 21507565640, 231287689900961870440, 21397598199889399837872215012598300187880, 228928604361955042169940915981517711585578107873998357253128210226981219949635080
Offset: 1

Views

Author

N. J. A. Sloane, Sep 15 2024

Keywords

Examples

			The initial values of S(n) are 5/8, 37/40, 677/680, 231877/231880, 21507565637/21507565640, 231287689900961870437/231287689900961870440, ...
		

Crossrefs

Showing 1-5 of 5 results.