A334027 "Look and say" the concatenated exponents in the prime factorization of n.

10, 11, 11, 12, 11, 21, 11, 13, 12, 21, 11, 1211, 11, 21, 21, 14, 11, 1112, 11, 1211, 21, 21, 11, 1311, 12, 21, 13, 1211, 11, 31, 11, 15, 21, 21, 21, 22, 11, 21, 21, 1311, 11, 31, 11, 1211, 1211, 21, 11, 1411, 12, 1112, 21, 1211, 11, 1113, 21, 1311, 21, 21, 11, 1221, 11

Offset

1,1

Links

Table of n, a(n) for n=1..61.

Eric Weisstein's World of Mathematics, Look and Say Sequence

Wikipedia, Look-and-say sequence

Formula

a(n) = A045918(A037916(n)).

Example

2 = 2^1 and there is one 1, so a(2) = 11.
3 = 3^1 and there is one 1, so a(3) = 11.
4 = 2^2 and there is one 2, so a(4) = 12.
5 = 5^1 and there is one 1, so a(5) = 11.
6 = 2^1*3^1 and there are two 1's, so a(6) = 21.
7 = 7^1 and there is one 1, so a(7) = 11.
8 = 2^3 and there is one 3, so a(8) = 13.
9 = 3^2 and there is one 2, so a(9) = 12.
10 = 2^1*5^1 and there are two 1's, so a(10) = 21.

Crossrefs

Cf. A037916, A045918.

Sequence in context: A065016 A087381 A136400 * A121266 A045988 A008947

Adjacent sequences: A334024 A334025 A334026 * A334028 A334029 A334030

Keyword

nonn,base

Author

Wesley Ivan Hurt, Apr 12 2020

Status

approved