cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A106547 Perfect squares n^2 which are neither the sum nor the difference of two primes (otherwise 0).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 121, 0, 0, 0, 0, 0, 289, 0, 0, 0, 0, 0, 529, 0, 625, 0, 0, 0, 0, 0, 961, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1681, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2601, 0, 2809, 0, 0, 0, 0, 0, 3481, 0, 0, 0, 0, 0, 4225, 0, 4489, 0, 0, 0, 0, 0, 5329, 0, 0, 0, 0, 0, 6241, 0, 0, 0, 6889, 0
Offset: 1

Views

Author

Alexandre Wajnberg, May 08 2005

Keywords

Crossrefs

Cf. A106544-A106548, A106562-A106564, A106571, A106573-A106575, A106577.

Formula

a(n) = Min(A106544(n), n^2-A106546(n)).

Extensions

Corrected and extended by Ray Chandler, May 12 2005

A106563 Numbers n such that n^2 is not the sum of two primes.

Original entry on oeis.org

1, 11, 17, 23, 25, 31, 39, 41, 45, 51, 53, 57, 59, 65, 67, 73, 79, 81, 83, 85, 87, 91, 95, 97, 99, 101, 105, 109, 111, 113, 115, 123, 125, 129, 133, 137, 141, 143, 147, 149, 151, 153, 157, 159, 163, 165, 167, 171, 175, 179, 181, 185, 187, 189, 193, 195, 197, 199, 201
Offset: 1

Views

Author

Alexandre Wajnberg, May 09 2005

Keywords

Examples

			a(3)=17 because the third square which is not the sum of two primes (289=17^2) is the 17th one in the succession of the perfect squares (thus: index 17).

Crossrefs

Cf. A106544-A106548, A106562-A106564, A106571, A106573-A106575, A106577.

Formula

a(n) = SQRT(A106562(n)).

Extensions

Extended by Ray Chandler, May 12 2005

A106574 Indices n of perfect squares n^2 which are neither the sum nor the difference of two primes.

Original entry on oeis.org

11, 17, 23, 25, 31, 41, 51, 53, 59, 65, 67, 73, 79, 83, 85, 87, 91, 95, 97, 101, 109, 113, 115, 125, 129, 133, 137, 141, 143, 149, 151, 153, 157, 159, 163, 165, 167, 175, 179, 181, 185, 187, 189, 193, 195, 197, 199, 201, 203, 207, 209, 213, 215, 221, 227, 229
Offset: 1

Views

Author

Alexandre Wajnberg, May 09 2005

Keywords

Examples

			a(2)=17 because the second square which is nor the sum nor the difference of two primes (289=17^2) is the 17th one in the succession of the perfect squares (thus: index 17).

Crossrefs

Cf. A106544-A106548, A106562-A106564, A106571, A106573-A106575, A106577.

Formula

a(n) = sqrt(A106573(n)).

Extensions

Corrected and extended by Ray Chandler, May 12 2005

A108321 a(n) = n^2 if n^2 is not the difference of two primes; otherwise a(n) = 0.

Original entry on oeis.org

0, 0, 0, 0, 25, 0, 49, 0, 0, 0, 121, 0, 169, 0, 0, 0, 289, 0, 361, 0, 0, 0, 529, 0, 625, 0, 729, 0, 841, 0, 961, 0, 0, 0, 1225, 0, 1369, 0, 0, 0, 1681, 0, 1849
Offset: 0

Views

Author

Alexandre Wajnberg, Jun 30 2005

Keywords

Comments

This sequence is also n^2 - A106546

Examples

			a(4)=0 because the fourth perfect square 16 is the difference between two primes: 19-3. a(5)=25 figures here because the nearest prime greater than 25 is 29 and the difference 29-25 is 4 (an even number >2), thus not a prime; all other greater primes are odd and the difference with 25 will give an even number, thus again not a prime.

Crossrefs

Cf. A106546, A106564, A098108, A106571.
Previous Showing 11-14 of 14 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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