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 1-4 of 4 results.

A113243 Differences of nonzero tetranacci numbers.

Original entry on oeis.org

0, 1, 2, 3, 4, 6, 7, 11, 13, 14, 21, 25, 27, 28, 41, 48, 52, 54, 55, 79, 93, 100, 104, 106, 107, 152, 179, 193, 200, 204, 206, 207, 293, 345, 372, 386, 393, 397, 399, 400, 565, 665, 717, 744, 758, 765, 769, 771, 772, 1089, 1282, 1382, 1434, 1461, 1475, 1482
Offset: 1

Views

Author

Jonathan Vos Post, Oct 19 2005; corrected Oct 20 2005

Keywords

Crossrefs

Programs

  • Maple
    isA113243 := proc(n)
        local i,j ;
        for j from 3 do
            for i from 3 to j do
                if A000078(j) - A000078(i) = n then
                    return true;
                elif A000078(j) - A000078(i) < n then
                    break ;
                end if;
            end do:
            if A000078(j) - A000078(j-1) > n then
                return false;
            end if;
        end do:
    end proc:
    for n from 0 to 10000 do
        if isA113243(n) then
            printf("%d,",n) ;
        end if;
    end do: # R. J. Mathar, Oct 04 2014
  • Mathematica
    Union[Flatten[Differences/@Subsets[Drop[LinearRecurrence[{1, 1, 1,1}, {0,0, 0, 1}, 16],3],{2}]]] (* James C. McMahon, Jun 23 2024 *)

Formula

{a(n)} = { A000078(i) - A000078(j) such that i>=j>=3 }.

A113293 First differences of Lucas 3-step numbers.

Original entry on oeis.org

0, 2, 4, 6, 8, 10, 14, 18, 20, 28, 32, 36, 38, 50, 60, 64, 68, 70, 92, 110, 120, 124, 128, 130, 170, 202, 220, 230, 234, 238, 240, 312, 372, 404, 422, 432, 436, 440, 442, 574, 684, 744, 776, 794, 804, 808, 812, 814, 1056, 1258, 1368, 1428, 1460, 1478, 1488
Offset: 1

Views

Author

Jonathan Vos Post, Oct 23 2005

Keywords

Comments

There are no primes in this sequence, except 2, as all values are odd, so all differences are even. Semiprimes include: a(3) = 4, a(4) = 6, a(6) = 10, a(7) = 14, a(13) = 38, a(26) = 202, a(35) = 422, a(44) = 794, a(54) = 1478, a(59) = 1942, a(66) = 2746, a(94) = 9326.

Examples

			a(0) = 0 because A001644(2)-A001644(0) = 3 - 3 = 0.
a(1) = 2 because A001644(2)-A001644(1) = 3 - 1 = 2.
a(2) = 4 because A001644(3)-A001644(2) = 7 - 3 = 4.
a(3) = 6 because A001644(3)-A001644(1) = 7 - 1 = 6.
a(75) = 5000 because A001644(14)-A001644(7) = 5071 - 71 = 5000.
		

Crossrefs

Formula

{a(n)} = { | A001644(i) - A001644(j) | such that i>=j}

A113294 First differences of Lucas 4-step numbers.

Original entry on oeis.org

1, 3, 4, 8, 11, 12, 19, 22, 23, 25, 36, 44, 47, 48, 73, 84, 92, 95, 96, 140, 165, 176, 184, 187, 188, 268, 316, 341, 352, 360, 363, 364, 517, 609, 657, 682, 693, 701, 704, 705, 998, 1174, 1266, 1314, 1339, 1350, 1358, 1361, 1362, 1923, 2264, 2440, 2532, 2580
Offset: 1

Views

Author

Jonathan Vos Post, Oct 23 2005

Keywords

Comments

Lucas 4-step numbers are also known as "Tetranacci Lucas numbers" or "Tetranacci numbers with different initial conditions" in A073817. Primes in this sequence are A113295. In this sequence are: 13340261 = 11 * 19 * 29 * 31 * 71 is a product of 5 distinct 2-digit primes; 95550683 = 269 * 593 * 599 is a product of 3 distinct 3-digit primes.

Examples

			a(0) = 1 because A073817(0)-A001644(2) = 4 - 3 = 1.
a(1) = 3 because A073817(3)-A001644(0) = 7 - 4 = 3.
a(2) = 4 because A073817(3)-A001644(2) = 7 - 3 = 4.
a(3) = 8 because A073817(4)-A001644(3) = 15 - 7 = 8.
a(122) = 70000 because A073817(17)-A001644(3) = 70007 - 7 = 70000.
		

Crossrefs

Formula

{a(n)} = { | A073817(i) - A073817(j) | such that i>=j }

A113295 Prime differences of Lucas 4-step numbers.

Original entry on oeis.org

3, 11, 19, 23, 47, 73, 701, 1361, 4363, 9067, 9749, 17477, 18743, 18839, 36293, 70003, 116101, 134917, 366437, 465061, 498749, 501013, 1844033, 3590099, 13305307, 13341259, 13341619, 36229121, 49069367, 49570721, 95550661, 351427309
Offset: 1

Views

Author

Jonathan Vos Post, Oct 23 2005

Keywords

Comments

These are primes from the sequence A113294, which is differences of Lucas 4-step numbers, also known as "Tetranacci Lucas numbers" or "Tetranacci numbers with different initial conditions" in A073817. Also in the difference set sequence are: 13340261 = 11 * 19 * 29 * 31 * 71 is a product of 5 distinct 2-digit primes; 95550683 = 269 * 593 * 599 is a product of 3 distinct 3-digit primes.

Examples

			a(1) = 3 because A073817(0)-A001644(1) = 4 - 1 = 3, a prime.
a(2) = 11 because A073817(4)-A001644(0) = 15 - 4 = 11, a prime.
a(3) = 19 because A073817(5)-A001644(3) = 26 - 7 = 19, a prime.
a(4) = 23 because A073817(5)-A001644(2) = 26 - 3 = 23, a prime.
a(16) = 70003 because A073817(17)-A001644(0) = 70007 - 4 = 70003, a prime.
		

Crossrefs

Formula

{a(n)} = Intersection of { | A073817(i) - A073817(j) | such that i>=j} and A000040. {a(n)} = Prime elements of { | A073817(i) - A073817(j) | such that i>=j}. {a(n)} = Prime elements of A113294.
Showing 1-4 of 4 results.