A161187 Let S = A089237\{0} = union of primes and nonzero squares; sequence gives indices of squares.

1, 4, 7, 10, 14, 17, 22, 26, 31, 35, 41, 46, 52, 58, 63, 70, 78, 84, 91, 98, 106, 114, 122, 129, 139, 148, 156, 165, 175, 184, 193, 204, 214, 225, 235, 246, 256, 266, 279, 291, 304, 316, 326, 339, 351, 365, 376, 390, 406, 417, 429, 445, 462, 475, 489, 501, 514

Offset: 1

Author

Daniel Tisdale, Jun 06 2009

Keywords

• easy
• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A089237. Complement of A161188.

Cf. A050052.

Programs

Haskell

a161187 n = a161187_list !! (n-1)
a161187_list = tail $ findIndices ((== 1) . a010052) a089237_list
-- Reinhard Zumkeller, Dec 18 2012

Magma

[1] cat [#PrimesUpTo(n^2-1)+n: n in [2..100]]; // Vincenzo Librandi, Feb 18 2016

Mathematica

Table[PrimePi[n^2 - 1] + n, {n, 60}] (* Vincenzo Librandi, Feb 18 2016 *)

Python

from sympy import primepi
def A161187(n): return n+primepi(n**2) # Chai Wah Wu, Oct 12 2024

Formula

A089237(a(n)+1) = A000290(n). - Reinhard Zumkeller, Dec 18 2012

Extensions

Edited by N. J. A. Sloane, Jun 07 2009

Extended by Ray Chandler, May 06 2010