A093151 -id:A093151 - cp's OEIS frontend

A093153 Difference between counts of odd composites in A093151 and A093152 [Count (1 mod 4) - count (3 mod 4)].

0, 1, 6, 9, 24, 146, 217, 445, 550, 5959, 14251, 63336, 118471, 183456, 951699, 3458333, 6284059, 2581690, 80743227, 259753424

Offset: 1

Enoch Haga, Mar 24 2004

In A091295 the counts are 1 higher. I computed the differences through 10^8 and the rest by extrapolating from A091098 and A091099. In the ranges given, the counts of odd composites less than 10^n are higher 1 mod 4 than 3 mod 4. They are exactly opposite for the primes less than 10^n where 3 mod 4 is higher.

			Below 10^3 there are 169 odd composites 1 mod 4 and 163 odd composites 3 mod 4, so a(3)=169-163=6

Cf. A093151 A093152 A091295 A091098 A091099.

Subtract count of odd composites 3 mod 4 less than 10^n from those 1 mod 4

a(n) = A093151(n) - A093152(n). For n>1, a(n) = A091099(n) - A091098(n) - 1. [From Max Alekseyev, May 17 2009]

More terms from Max Alekseyev, May 17 2009

A093152 Number of odd composites below 10^n that are congruent to 3 modulo 4.

Original entry on oeis.org

0, 12, 163, 1881, 20192, 210678, 2167602, 22119050, 224575958, 2272470765, 22940965468, 231196012323, 2326967172345, 23397529032871, 235077714312816, 2360380827753871, 23688221418030854, 237630022854838725, 2382971166321456083, 23889590198589663868

Offset: 1

Enoch Haga, Mar 24 2004

nonn

			Below 10^2 there are 12 odd composites 3 mod 4 so a(2)=12

Cf. A093151 A093153 A091295 A091098 A091099.

For n>1, a(n) = 25*10^(n-2) - A091099(n) [From Max Alekseyev, May 17 2009]

a(9) from Ryan Propper, Jun 21 2005

a(10)-a(20) from Max Alekseyev, May 17 2009, Oct 08 2013

cp's OEIS Frontend

A093153 Difference between counts of odd composites in A093151 and A093152 [Count (1 mod 4) - count (3 mod 4)].

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