A363572 Lexicographically earliest sequence of distinct terms > 0 such that the concatenation of the rightmost digit of a(n) and the leftmost digit of a(n+1) forms a prime number. The rightmost digit of a(n) cannot be 0.

1, 3, 7, 9, 71, 11, 12, 31, 13, 14, 15, 32, 33, 16, 17, 18, 34, 19, 72, 35, 36, 73, 74, 37, 38, 39, 75, 91, 76, 77, 92, 93, 78, 94, 79, 701, 95, 96, 101, 97, 98, 99, 702, 301, 102, 302, 303, 103, 104, 105, 304, 106, 107, 108, 305, 306, 109, 703, 111, 112, 307, 113, 114, 115

Offset

1,2

Links

Tyler Busby, Table of n, a(n) for n = 1..10000

Eric Angelini, Prime welds, Personal blog.

Example

a(1) = 1 and a(2) = 3 form 13, a prime number;
a(2) = 3 and a(3) = 7 form 37, a prime number;
a(3) = 7 and a(4) = 9 form 79, a prime number;
a(4) = 9 and the leftmost digit of a(5) = 71 form 97, a prime number;
a(5) = 71 and its rightmost digit, concatenated to the leftmost digit of a(6) = 11, form 11, a prime number; etc.

Crossrefs

Cf. A152607.

Sequence in context: A003033 A193945 A087147 * A337613 A152607 A118559

Adjacent sequences: A363569 A363570 A363571 * A363573 A363574 A363575

Keyword

base,nonn

Author

Eric Angelini, Aug 17 2023

Status

approved