A093152 -id:A093152 - 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

A093151 Number of odd composites 1 mod 4 less than 10^n.

Original entry on oeis.org

1, 13, 169, 1890, 20216, 210824, 2167819, 22119495, 224576508, 2272476724, 22940979719, 231196075659, 2326967290816, 23397529216327, 235077715264515, 2360380831212204, 23688221424314913, 237630022857420415, 2382971166402199310, 23889590198849417292

Offset: 1

Enoch Haga, Mar 24 2004

nonn

			Below 10^2 there are 13 odd composites so a(2)=13

Cf. A093152 A093153 A091295 A091098 A091099.

Count odd composites 1 mod 4 less than 10^n

For n>1, a(n) = 25*10^(n-2) - 1 - A091098(n). - Max Alekseyev, May 30 2007

More terms from Max Alekseyev, May 30 2007

Extended by Max Alekseyev, Oct 13 2009

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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