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 1-3 of 3 results.

A036262 Array of numbers read by upward antidiagonals, arising from Gilbreath's conjecture: leading row lists the primes; the following rows give absolute values of differences of previous row.

Original entry on oeis.org

2, 1, 3, 1, 2, 5, 1, 0, 2, 7, 1, 2, 2, 4, 11, 1, 2, 0, 2, 2, 13, 1, 2, 0, 0, 2, 4, 17, 1, 2, 0, 0, 0, 2, 2, 19, 1, 2, 0, 0, 0, 0, 2, 4, 23, 1, 2, 0, 0, 0, 0, 0, 2, 6, 29, 1, 0, 2, 2, 2, 2, 2, 2, 4, 2, 31, 1, 0, 0, 2, 0, 2, 0, 2, 0, 4, 6, 37, 1, 0, 0, 0, 2, 2, 0, 0, 2, 2, 2, 4, 41, 1, 0, 0, 0, 0, 2, 0, 0, 0
Offset: 0

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Author

N. J. A. Sloane

Keywords

Comments

The conjecture is that the leading term is always 1.
Odlyzko has checked it for primes up to pi(10^13) = 3*10^11.
From M. F. Hasler, Jun 02 2012: (Start)
The second column, omitting the initial 3, is given in A089582. The number of "0"s preceding the first term > 1 in the n-th row is given in A213014. The first term > 1 in any row must equal 2, else the conjecture is violated: Obviously all terms except for the first one are even. Thus, if the 2nd term in some row is > 2, it is >= 4, and the first term of the subsequent row is >= 3. If there is a positive number of zeros preceding a first term > 2 (thus >= 4), this "jump" will remain constant and "propagate" (in subsequent rows) to the beginning of the row, and the previously discussed case applies.
The previous statement can also be formulated as: Gilbreath's conjecture is equivalent to: A036277(n) > A213014(n)+2 for all n.
CAVEAT: While table A036261 starts with the first absolute differences of the primes in its first row, the present sequence has the primes themselves in its uppermost row, which is sometimes referred to as "row 0". Thus, "first row" of this table A036262 may either refer to row 1 (1,2,2,...), or to row 0 (2,3,5,7,...), while the latter might, however, as well be referred to "row 1 of A036262" in other sequences or papers.
(End)
From Clark Kimberling, Nov 27 2022: (Start)
Suppose that S = (s(k)), for k >= 1, is a sequence of real numbers. For n >= 1, let g(1,n) = |s(n+1)-s(n)| and g(k,n) = |g(k-1,n+1) - g(k-1,n)| for k >= 2.
Call (g(k,n)) the Gilbreath array of S. Call the first column of this array the Gilbreath transform of S. Denote this transform by G(S), so that G(S) is the sequence (g(n,1)). If S is the sequence of primes, then the Gilbreath conjecture holds that G(S) consists exclusively of 1's. More generally, it appears that there are many S such that G(S) is eventually periodic. See A358691 for conjectured examples. (End)

Examples

			The array begins (conjecture is leading term is always 1):
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101
1 2 2 4  2  4  2  4  6  2  6  4  2  4  6  6  2  6  4  2  6  4  6  8  4   2
1 0 2 2  2  2  2  2  4  4  2  2  2  2  0  4  4  2  2  4  2  2  2  4  2   2
1 2 0 0  0  0  0  2  0  2  0  0  0  2  4  0  2  0  2  2  0  0  2  2  0   0
1 2 0 0  0  0  2  2  2  2  0  0  2  2  4  2  2  2  0  2  0  2  0  2  0   0
1 2 0 0  0  2  0  0  0  2  0  2  0  2  2  0  0  2  2  2  2  2  2  2  0   8
1 2 0 0  2  2  0  0  2  2  2  2  2  0  2  0  2  0  0  0  0  0  0  2  8   8
1 2 0 2  0  2  0  2  0  0  0  0  2  2  2  2  2  0  0  0  0  0  2  6  0   8
1 2 2 2  2  2  2  2  0  0  0  2  0  0  0  0  2  0  0  0  0  2  4  6  8   6
1 0 0 0  0  0  0  2  0  0  2  2  0  0  0  2  2  0  0  0  2  2  2  2  2   4
...

References

  • R. K. Guy, Unsolved Problems Number Theory, A10.
  • H. L. Montgomery, Ten Lectures on the Interface Between Analytic Number Theory and Harmonic Analysis, Amer. Math. Soc., 1996, p. 208.
  • Paulo Ribenboim, The Little Book of Bigger Primes, Springer-Verlag NY 2004. See p. 192.
  • W. Sierpiński, L'induction incomplète dans la théorie des nombres, Scripta Math. 28 (1967), 5-13.
  • C. A. Pickover, The Math Book, Sterling, NY, 2009; see p. 410.

Links

Crossrefs

Cf. A001223, A036261, A036277, A054977, A222310, A358691, A089582 (2nd col).
See A255483 for an interesting generalization.

Programs

  • Haskell
    a036262 n k = delta !! (n - k) !! (k - 1) where delta = iterate
   (\pds -> zipWith (\x y -> abs (x - y)) (tail pds) pds) a000040_list
-- Reinhard Zumkeller, Jan 23 2011
  • Maple
    A036262 := proc(n, k)
    option remember ;
    if n = 0 then
        ithprime(k) ;
    else
        abs(procname(n-1, k+1)-procname(n-1, k)) ;
    end if;
end proc:
seq(seq( A036262(d-k,k),k=1..d),d=1..13) ; # R. J. Mathar, May 10 2023
  • Mathematica
    max = 14; triangle = NestList[ Abs[ Differences[#]] &, Prime[ Range[max]], max]; Flatten[ Table[ triangle[[n - k + 1, k]], {n, 1, max}, {k, 1, n}]] (* Jean-François Alcover, Nov 04 2011 *)

Formula

T(0,k) = A000040(k). T(n,k) = |T(n-1,k+1) - T(n-1,k)|, n > 0. - R. J. Mathar, Sep 19 2013

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 23 2003
Definition edited by N. J. A. Sloane, May 03 2023

A000232 Construct a triangle as in A036262. Sequence is one less than the position of the first number larger than 2 in the n-th row (n-th difference).

Original entry on oeis.org

3, 8, 14, 14, 25, 24, 23, 22, 25, 59, 98, 97, 98, 97, 174, 176, 176, 176, 176, 291, 290, 289, 740, 874, 873, 872, 873, 872, 871, 870, 869, 868, 867, 866, 2180, 2179, 2178, 2177, 2771, 2770, 2769, 2768, 2767, 2766, 2765, 2764, 2763, 2763, 2763, 2763, 3366, 4208, 4207
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Comments

Related to Gilbreath conjecture.

References

  • W. Sierpiński, A Selection of Problems in the Theory of Numbers. Macmillan, NY, 1964, p. 35.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Crossrefs

Cf. A001549.

Programs

  • Maple
    A000232 := proc(n)
    local k;
    for k from 1 do
        if A036262(n,k) > 2 then
            return k-1 ;
        end if;
    end do:
end proc:
seq(A000232(n),n=1..40) ; # R. J. Mathar, May 10 2023
  • Mathematica
    max = 10^4; triangle = NestList[Abs[Differences[#]] &, Prime[Range[max]], max]; a[n_] := (p = Position[triangle[[n + 1]], k_ /; k > 2, 1, 1]; If[p == {}, Nothing, p[[1, 1]] - 1]); Table[a[n], {n, 1, Sqrt[max]}] (* Jean-François Alcover, Feb 06 2016 *)

Formula

a(n) = A036277(n) - 1. - T. D. Noe, Feb 03 2007

Extensions

Edited by Robert G. Wilson v, Aug 18 2002
More terms from Jean-François Alcover, Feb 06 2016

A001549 Related to Gilbreath conjecture.

Original entry on oeis.org

4, 10, 17, 18, 30, 34, 69, 109, 111, 189, 192, 193, 194, 195, 311, 763, 898, 900, 2215, 2810, 2811, 2812, 2813, 3417, 4260, 6000, 6002, 6003, 6004, 23331, 31569, 31601, 31602, 31605, 31606, 31617, 31625, 31627, 92716, 104071, 141818, 141819, 271743, 271747, 325218
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Comments

Records in the sequence n+A000232(n) = 4, 10, 17, 18, 30, 30, 30, 30, 34, 69, 109, 109, 111, 111, 189, 192, 193,... - R. J. Mathar, May 10 2023

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Crossrefs

Cf. A000232, A036277.
Showing 1-3 of 3 results.

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

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