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 1-6 of 6 results.

A062964 Pi in hexadecimal.

Original entry on oeis.org

3, 2, 4, 3, 15, 6, 10, 8, 8, 8, 5, 10, 3, 0, 8, 13, 3, 1, 3, 1, 9, 8, 10, 2, 14, 0, 3, 7, 0, 7, 3, 4, 4, 10, 4, 0, 9, 3, 8, 2, 2, 2, 9, 9, 15, 3, 1, 13, 0, 0, 8, 2, 14, 15, 10, 9, 8, 14, 12, 4, 14, 6, 12, 8, 9, 4, 5, 2, 8, 2, 1, 14, 6, 3, 8, 13, 0, 1, 3, 7, 7, 11, 14, 5, 4, 6, 6, 12, 15, 3, 4, 14, 9
Offset: 1

Views

Author

Robert Lozyniak (11(AT)onna.com), Jul 22 2001

Keywords

Comments

Bailey and Crandall conjecture that the terms of this sequence, apart from the first, are given by the formula floor(16*(x(n) - floor(x(n)))), where x(n) is determined by the recurrence equation x(n) = 16*x(n-1) + (120*n^2 - 89*n + 16)/(512*n^4 - 1024*n^3 + 712*n^2 - 206*n + 21) with the initial condition x(0) = 0 (see A374334). They have numerically verified the conjecture for the first 100000 terms of the sequence. - Peter Bala, Oct 31 2013
Bailey, Borwein & Plouffe's ("BBP") formula allows one to compute the n-th hexadecimal digit of Pi without calculating the preceding digits (see Wikipedia link). - M. F. Hasler, Mar 14 2015

Examples

			3.243f6a8885a308d3...
		

References

  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 17-28.

Crossrefs

Pi in base b: A004601 (b=2), A004602 (b=3), A004603 (b=4), A004604 (b=5), A004605 (b=6), A004606 (b=7), A006941 (b=8), A004608 (b=9), A000796 (b=10), A068436 (b=11), A068437 (b=12), A068438 (b=13), A068439 (b=14), A068440 (b=15), this sequence (b=16), A060707 (b=60).

Programs

  • Mathematica
    RealDigits[ N[ Pi, 115], 16] [[1]]
  • PARI
    { default(realprecision, 24300); x=Pi; for (n=1, 20000, d=floor(x); x=(x-d)*16; write("b062964.txt", n, " ", d)); } \\ Harry J. Smith, Apr 27 2009
    
  • PARI
    N=50; default(realprecision,.75*N); A062964=digits(Pi*16^N\1,16) \\ M. F. Hasler, Mar 14 2015

Formula

a(n) = 8*A004601(4n) + 4*A004601(4n+1) + 2*A004601(4n+2) + 1*A004601(4n+3).
If Pi is the expansion of Pi in base 10, Pi=3.1415926...: a(n) = floor(16^n*Pi) - 16*floor(16^(n-1)*Pi). - Benoit Cloitre, Mar 09 2002

Extensions

More terms from Henry Bottomley, Jul 24 2001

A374335 a(n) is the denominator of x(n) = (16*x(n-1) + (120*n^2 - 89*n + 16)/(512*n^4 - 1024*n^3 + 712*n^2 - 206*n + 21)) mod 1, with x(0) = 0.

Original entry on oeis.org

1, 15, 4095, 765765, 111035925, 78058255275, 24536311574775, 81926744348173725, 154923473562396513975, 154923473562396513975, 595232293160786606325, 76784965817741472215925, 321191512015612578279214275, 3146713243216956429401462252175, 342991743510648250804759385487075
Offset: 0

Views

Author

Paolo Xausa, Jul 06 2024

Keywords

Comments

See A374334 for details and links.

Crossrefs

Cf. A374333, A374334 (numerators), A374581, A374608.

Programs

  • Mathematica
    Block[{n = 0}, Denominator[NestList[Mod[16*# + (120*(++n)^2 - 89*n + 16)/(512*n^4 - 1024*n^3 + 712*n^2 - 206*n + 21), 1] &, 0, 20]]]

A374332 a(n) is the numerator of x(n) = (2*x(n-1) + 1/n) mod 1, with x(0) = 0.

Original entry on oeis.org

0, 0, 1, 1, 11, 1, 7, 64, 289, 1007, 44, 338, 163, 3505, 8297, 44488, 27221, 823117, 993287, 20403983, 26327699, 27713369, 27650353, 315868349, 2488325579, 6016553239, 1399433807, 3562923992, 9142117861, 275160597119, 268889538733, 3968532770473, 114095155444597
Offset: 0

Views

Author

Paolo Xausa, Jul 06 2024

Keywords

Comments

A constant alpha, defined as alpha = Sum_{n >= 1} p(n)/(q(n)*b^n), is b-normal if and only if the associated sequence, defined by x(0) = 0 and x(n) = (b*x(n-1) + p(n)/q(n)) mod 1, is equidistributed in the unit interval.
The present sequence gives the numerators of the associated sequence for alpha = log(2) (where b = 2). See Bailey and Borwein (2005), p. 505 (first example of Theorem 3).
Denominators are given by A374333.

Crossrefs

Cf. A002162, A374333 (denominators), A374334, A374336.

Programs

  • Mathematica
    Block[{n = 0}, Numerator[NestList[Mod[2*# + 1/++n, 1] &, 0, 50]]]
  • PARI
    x(n) = if (n==0, 0, 2*x(n-1) + 1/n);
    a(n) = numerator(frac(x(n))); \\ Michel Marcus, Jul 13 2024
  • Python
    from fractions import Fraction
    from itertools import count, islice
    def A374332_gen(): # generator of terms
        a = Fraction(0,1)
        for n in count(1):
            yield a.numerator
            a = (2*a+Fraction(1,n)) % 1
    A374332_list = list(islice(A374332_gen(),20)) # Chai Wah Wu, Jul 13 2024
    

A374580 a(n) is the numerator of (120*n^2 + 151*n + 47)/(512*n^4 + 1024*n^3 + 712*n^2 + 194*n + 15).

Original entry on oeis.org

47, 106, 829, 316, 857, 3802, 5273, 776, 1787, 11126, 4519, 16228, 19139, 1486, 25681, 29312, 3687, 37294, 8329, 15412, 51067, 56138, 20483, 2680, 72791, 8758, 85093, 91604, 6557, 105346, 112577, 40016, 127759, 27142, 15989, 152332, 161003, 56638, 35813, 188456
Offset: 0

Views

Author

Paolo Xausa, Jul 12 2024

Keywords

Comments

See Bailey and Crandall (2001), section 5 (pp. 183-184) for a derivation of this rational polynomial.
Denominators are given by A374581.

Crossrefs

Cf. A000796, A001025, A374334, A374581 (denominators), A374607.

Programs

  • Mathematica
    A374580[n_] := Numerator[(120*n^2 + 151*n + 47)/(512*n^4 + 1024*n^3 + 712*n^2 + 194*n + 15)];
    Array[A374580, 50, 0]
  • Python
    from math import gcd
    def A374580(n): return (lambda p,q: p//gcd(p,q))(n*(120*n + 151) + 47,n*(n*(n*(512*n + 1024) + 712) + 194) + 15) # Chai Wah Wu, Jul 14 2024

Formula

Sum_{n >= 0} (1/16^n)*a(n)/A374581(n) = A000796. See Bailey and Crandall (2001), eq. 5-2, p. 184.

A374607 a(n) is the numerator of (1134*n^3 + 2097*n^2 + 1188*n + 193)/(10368*n^4 + 20736*n^3 + 14112*n^2 + 3744*n + 320).

Original entry on oeis.org

193, 1153, 20029, 832, 111073, 50077, 327757, 7816, 724513, 251857, 1355773, 55511, 2275969, 715357, 3539533, 134909, 5200897, 1549441, 7314493, 133717, 9934753, 2862973, 13116109, 233347, 16912993, 4764817, 21379837, 746297, 26571073, 7363837, 32541133, 1119851
Offset: 0

Views

Author

Paolo Xausa, Jul 13 2024

Keywords

Comments

See Bailey and Crandall (2001), section 5 (pp. 183-185) for a derivation of this rational polynomial.
Denominators are given by A374608.

Crossrefs

Cf. A000796, A010482, A089357, A374334, A374580, A374608 (denominators).

Programs

  • Mathematica
    A374607[n_] := Numerator[(1134*n^3 + 2097*n^2 + 1188*n + 193)/(10368*n^4 + 20736*n^3 + 14112*n^2 + 3744*n + 320)];
    Array[A374607, 50, 0]
  • Python
    from math import gcd
    def A374607(n): return (p:=n*(n*(1134*n + 2097) + 1188) + 193)//gcd(p,n*(n*(n*(324*n + 648) + 441) + 117) + 10<<5) # Chai Wah Wu, Jul 14 2024

Formula

sqrt(27)*(Sum_{n >= 0} (1/64^n)*a(n)/A374608(n)) = A000796. See Bailey and Crandall (2001), p. 185.

A374336 a(n) is the numerator of x(n) = (2*x(n-1) + c(n)) mod 1, where c(n) = 1/n if n is a power of 3 and 0 otherwise, with x(0) = 0.

Original entry on oeis.org

0, 0, 0, 1, 2, 1, 2, 1, 2, 4, 8, 7, 5, 1, 2, 4, 8, 7, 5, 1, 2, 4, 8, 7, 5, 1, 2, 13, 26, 25, 23, 19, 11, 22, 17, 7, 14, 1, 2, 4, 8, 16, 5, 10, 20, 13, 26, 25, 23, 19, 11, 22, 17, 7, 14, 1, 2, 4, 8, 16, 5, 10, 20, 13, 26, 25, 23, 19, 11, 22, 17, 7, 14, 1, 2, 4
Offset: 0

Views

Author

Paolo Xausa, Jul 06 2024

Keywords

Comments

A constant alpha, defined as alpha = Sum_{n >= 1} p(n)/(q(n)*b^n), is b-normal if and only if the associated sequence, defined by x(0) = 0 and x(n) = (b*x(n-1) + p(n)/q(n)) mod 1, is equidistributed in the unit interval.
The present sequence gives the numerators of the associated sequence (where b = 2) for alpha_0 = Sum_{n >= 1} 1/((3^n)*2^(3^n)) = A192014. See Bailey and Borwein (2005), pp. 505-506 (third example of Theorem 3). They show that alpha_0, as well as any constant defined as Sum_{n >= 1} 1/((3^n)*2^(3^n+r_n)) (where r_n is the n-th binary digit of the real number r in the [0,1) interval), is 2-normal and transcendental.
Bailey and Borwein also note that terms follow a pattern of triply repeating segments, each of length 2*3^m and containing all integers relative prime to and less than 3^(m+1).
Denominators are given by A365458.

Crossrefs

Cf. A192014, A374332, A374334, A365458 (denominators).

Programs

  • Mathematica
    Block[{n = 0}, Numerator[NestList[Mod[2*# + If[IntegerQ[Log[3, ++n]], 1/n, 0], 1] &, 0, 100]]]
Showing 1-6 of 6 results.