A308830 - OEIS

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A308830

a(n) is the smallest positive integer such that the concatenation, in base 2, of the first n terms is divisible by n.

1

1, 2, 3, 4, 5, 2, 9, 8, 5, 2, 3, 20, 7, 14, 27, 16, 11, 30, 11, 20, 15, 22, 31, 24, 11, 14, 11, 20, 15, 10, 35, 32, 1, 26, 97, 92, 53, 18, 31, 56, 91, 10, 3, 12, 27, 30, 15, 48, 37, 78, 23, 108, 9, 6, 49, 8, 51, 54, 87, 60, 79, 26, 25, 64, 111, 122, 117, 28

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

This sequence is the binary variant of A099552.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..8192

Rémy Sigrist, PARI program for A308830

FORMULA

a(2^k) = 2^k for any k >= 0.

A007814(a(n)) = A007814(n).

EXAMPLE

The first terms, alongside the concatenation of the first n terms, both in decimal and in base 2, are:

n a(n) bin(a(n)) K(n) bin(K(n))

-- ---- --------- -------- --------------------------

1 1 1 1 1

2 2 10 6 110

3 3 11 27 11011

4 4 100 220 11011100

5 5 101 1765 11011100101

6 2 10 7062 1101110010110

7 9 1001 113001 11011100101101001

8 8 1000 1808024 110111001011010011000

9 5 101 14464197 110111001011010011000101

10 2 10 57856790 11011100101101001100010110

PROG

(PARI) See Links section.

CROSSREFS

Cf. A007814, A099552.

Sequence in context: A333696 A134364 A338579 * A343252 A341355 A104413

Adjacent sequences: A308827 A308828 A308829 * A308831 A308832 A308833

KEYWORD

nonn,base

AUTHOR

Rémy Sigrist, Jun 27 2019

STATUS

approved