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 1-2 of 2 results.

A363186 Lexicographically earliest sequence of distinct positive integers such that the sum of all terms a(1)..a(n) is a substring of the concatenation of all terms a(1)..a(n).

Original entry on oeis.org

1, 10, 98, 767, 111, 122, 2, 11, 100, 889, 110, 4490, 400, 560, 1096, 124, 20, 129, 70, 502, 93, 171, 212, 361, 512, 26, 21, 36, 54, 14, 1011, 139, 99, 59, 550, 684, 345, 102, 1021, 1999, 2871, 137, 892, 89, 126, 875, 510, 994, 586, 2012, 662, 1836, 201, 405, 388, 2007, 2798, 1641, 50, 340
Offset: 1

Views

Author

Scott R. Shannon and Eric Angelini, Jul 07 2023

Keywords

Comments

In the first 10000 terms the smallest number that has not yet appeared is 696; it is therefore likely all numbers eventually appear although this is unknown.

Examples

			a(2) = 10 as a(1) + 10 = 1 + 10 = 11 which is a substring of "1" + "10" = "110".
a(3) = 98 as a(1) + a(2) + 98 = 1 + 10 + 98 = 109 which is a substring of "1" + "10" + "98" = "11098".
a(4) = 767 as a(1) + a(2) + a(3) + 767 = 1 + 10 + 98 + 767 = 876 which is a substring of "1" + "10" + "98" + "767" = "11098767".
		

Crossrefs

Programs

  • Python
    from itertools import islice
    def agen(): # generator of terms
        s, mink, aset, concat = 1, 2, {1}, "1"
        yield from [1]
        while True:
            an = mink
            while an in aset or not str(s+an) in concat+str(an): an += 1
            aset.add(an); s += an; concat += str(an); yield an
            while mink in aset: mink += 1
    print(list(islice(agen(), 60))) # Michael S. Branicky, Feb 08 2024

A364201 Lexicographically earliest sequence of distinct positive integers such that the sum of all terms a(1)..a(n) in binary is a substring of the concatenation of all terms a(1)..a(n) in binary.

Original entry on oeis.org

1, 2, 3, 5, 11, 7, 16, 9, 6, 18, 4, 13, 10, 15, 12, 23, 20, 8, 27, 19, 36, 26, 22, 17, 21, 31, 25, 14, 29, 28, 30, 57, 24, 32, 39, 43, 40, 34, 38, 46, 33, 35, 42, 37, 55, 44, 58, 48, 56, 52, 41, 45, 64, 63, 54, 61, 60, 49, 50, 51, 65, 47, 67, 88, 132, 73, 76, 68, 109, 59, 82, 87, 62, 98, 69, 70
Offset: 1

Views

Author

Scott R. Shannon, Jul 13 2023

Keywords

Comments

In the first 10000 terms the smallest number that has not yet appeared is 7026; it is conjectured all numbers eventually appear.
The fixed points begin 1, 2, 3, 29, 48, 68, 96, 182, 471, 839, ... . It is likely there are infinitely more.

Examples

			a(2) = 2 as a(1) + 2 = 1 + 2 = 3 = 11_2, which is a substring of "a(1)"_2 + "2"_2 = "1" + "10" = "110".
a(4) = 5 as a(1) + a(2) + a(3) + 5 = 1 + 2 + 3 + 5 = 11 = 1011_2, which is a substring "a(1)"_2 + "a(2)"_2 + "a(3)"_2 + "5"_2 = "1" + "10" + "11" + "101" = "11011101".
a(5) = 11 as a(1) + a(2) + a(3) + a(4) + 11 = 1 + 2 + 3 + 5 + 11 = 22 = 10110_2, which is a substring "a(1)"_2 + "a(2)"_2 + "a(3)"_2 + "a(4)"_2 + "11"_2 = "1" + "10" + "11" + "101" + "1011" = "110111011011".
		

Crossrefs

Showing 1-2 of 2 results.