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A333995 a(n) = number of distinct composite numbers in the n X n multiplication that are not in the n-1 X n-1 multiplication table. 3
0, 1, 2, 3, 4, 4, 6, 5, 6, 6, 10, 6, 12, 8, 9, 8, 16, 9, 18, 10, 12, 12, 22, 10, 16, 14, 15, 13, 28, 12, 30, 15, 18, 18, 20, 13, 36, 20, 21, 16, 40, 17, 42, 20, 21, 24, 46, 17, 31, 22, 27, 23, 52 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..53.

FORMULA

a(n) = n - A108407(n-1) - A010051(n), n>1. - Corrected by R. J. Mathar, Oct 02 2020

EXAMPLE

a(2) = 1 since the 1X1 and 2X2 multiplication tables are

---

  1

---

  1 2

  2 4

---

and the composite number 4 has appeared.

---

a(8)=5:

.1..2..3..4..5..6..7....8

....4..6..8.10.12.14...16

.......9.12.15.18.21...24

.........16.20.24.28...32 *

............25.30.35...40 *

...............36.42...48 *

..................49...56 *

.......................64 *

CROSSREFS

Cf. A010051, A108407.

Sequence in context: A008328 A298933 A091860 * A301764 A181833 A202650

Adjacent sequences:  A333992 A333993 A333994 * A333996 A333997 A333998

KEYWORD

nonn

AUTHOR

Charles Kusniec, Sep 05 2020

STATUS

approved

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Last modified January 15 13:34 EST 2021. Contains 340187 sequences. (Running on oeis4.)