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A065893 Which composite number is the square of n? Index of n^2 in A002808. 2
0, 1, 4, 9, 15, 24, 33, 45, 58, 74, 90, 109, 129, 151, 176, 201, 227, 257, 288, 321, 355, 391, 429, 470, 510, 553, 599, 646, 694, 745, 798, 851, 907, 964, 1024, 1085, 1149, 1215, 1280, 1348, 1417, 1489, 1565, 1640, 1718, 1796, 1879, 1961, 2043, 2132, 2222 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

EXAMPLE

n = 5 and 25 is the 15th composite number: 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25.

MATHEMATICA

Table[n^2-(PrimePi[n^2])-1, {w, 1, 128}]

PROG

(PARI) { default(primelimit, 4294965247); for (n=1, 1000, f=n^2; a=f - primepi(f) - 1; write("b065893.txt", n, " ", a) ) } \\ Harry J. Smith, Nov 04 2009

CROSSREFS

Cf. A002808, A000290, A000720.

Sequence in context: A184005 A194106 A004629 * A052116 A109641 A134675

Adjacent sequences:  A065890 A065891 A065892 * A065894 A065895 A065896

KEYWORD

nonn

AUTHOR

Labos Elemer, Nov 28 2001

STATUS

approved

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Last modified May 8 13:26 EDT 2021. Contains 343666 sequences. (Running on oeis4.)