A088612 a(1) = 1, a(n) = n-th squarefree number if n is not squarefree else a(n) is the n-th nonsquarefree number.

1, 8, 9, 5, 16, 18, 20, 11, 13, 27, 28, 17, 36, 40, 44, 23, 48, 29, 50, 31, 54, 56, 60, 37, 38, 68, 41, 42, 76, 80, 81, 51, 88, 90, 92, 58, 98, 99, 100, 65, 108, 112, 116, 70, 71, 121, 124, 77, 78, 79, 132, 83, 136, 86, 144, 89, 148, 150, 152, 95, 156, 160, 102, 103, 168

Offset

1,2

Links

Table of n, a(n) for n=1..65.

Example

a(9) = 13, the 9th squarefree number, A005117(9).

Prog

(Python)
# uses programs from A005117 and A013929
from sympy import factorint
def A088612(n): return A013929(n) if max(factorint(n).values(), default=0)<2 and n>1 else A005117(n) # Chai Wah Wu, Aug 12 2024

Crossrefs

Cf. A005117, A013929, A088611.

Sequence in context: A245772 A190289 A198119 * A225426 A093626 A154208

Adjacent sequences: A088609 A088610 A088611 * A088613 A088614 A088615

Keyword

nonn

Author

Amarnath Murthy, Oct 16 2003

Extensions

Corrected and extended by Ray Chandler, Oct 18 2003

Status

approved