

A109227


Binary strings that have 1's where primes occur, 0's elsewhere and every term ends with the nth prime index.


2



1, 11, 1101, 110101, 1101010001, 110101000101, 1101010001010001, 110101000101000101, 1101010001010001010001, 1101010001010001010001000001, 110101000101000101000100000101, 110101000101000101000100000101000001
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

a(2) and a(121) are primes. Are there any more?


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..168


EXAMPLE

a(4) = 110101 because the string '00110101' has 1's at the prime indices 2,3,5,7 and the first two zeros are dropped.


MATHEMATICA

a[n_] := FromDigits[Boole @ PrimeQ[Range[Prime[n]]]]; Array[a, 12] (* Amiram Eldar, Aug 18 2020 *)


CROSSREFS

Cf. A109228.
Sequence in context: A348269 A153435 A266787 * A133342 A110574 A280042
Adjacent sequences: A109224 A109225 A109226 * A109228 A109229 A109230


KEYWORD

base,easy,nonn


AUTHOR

Jason Earls, Jun 23 2005


STATUS

approved



