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.

Showing 1-5 of 5 results.

A243367 Primes p such that p^2+10 is prime.

Original entry on oeis.org

3, 7, 11, 13, 31, 53, 59, 71, 83, 97, 101, 127, 151, 157, 179, 181, 211, 223, 227, 239, 311, 367, 379, 449, 487, 521, 599, 601, 613, 619, 631, 743, 773, 809, 827, 883, 977, 1009, 1021, 1039, 1091, 1093, 1103, 1117, 1193, 1201, 1217, 1249, 1427, 1471, 1481, 1483, 1487, 1567
Offset: 1

Views

Author

Zak Seidov, Jun 04 2014

Keywords

Crossrefs

Cf. A182475.

Programs

  • PARI
    isok(p) = isprime(p) && isprime(p^2+10); \\ Michel Marcus, Jun 04 2014

Formula

a(n) = sqrt(A182475(n)-10).

A182476 Primes of the form p^2+100, where p is prime.

Original entry on oeis.org

109, 149, 269, 389, 461, 941, 1061, 1949, 2309, 2909, 3581, 3821, 10301, 10709, 11549, 11981, 16229, 18869, 19421, 22901, 24749, 26669, 30029, 32141, 44621, 52541, 57221, 72461, 76829, 94349, 96821, 109661, 128981, 134789, 167381, 201701, 214469, 253109
Offset: 1

Views

Author

Alex Ratushnyak, May 01 2012

Keywords

Crossrefs

Cf. A045637 (p^2 + 4 is prime), A079141 (p^2 + 6 is prime), A182475.

Programs

  • Mathematica
    Select[Table[p^2 + 100, {p, Prime[Range[200]]}], PrimeQ] (* T. D. Noe, May 01 2012 *)

A217717 Primes of the form x^2 + y^2 - 1, where x and y are primes.

Original entry on oeis.org

7, 17, 73, 97, 193, 241, 313, 337, 409, 457, 577, 1009, 1129, 1201, 1249, 1321, 1489, 1657, 1801, 1873, 2017, 2137, 2377, 2521, 2689, 2833, 2857, 3049, 3169, 3217, 3361, 3529, 3697, 3769, 3889, 4057, 4177, 4441, 4513, 4561, 4657, 5209, 5449, 5569, 5689, 5857
Offset: 1

Views

Author

Keywords

Comments

Unlike primes of the form x^2+y^2 (A045637) which can be redefined as x^2+4, and primes of the form x^2+y^2+1 (A182475) which can be redefined as primes of the form x^2+10, this sequence appears to have no one-variable analog. In the preceding, x and y are prime.

Examples

			457 is in the sequence because it is a prime number, and 457 = 13^2 + 17^2 - 1.
		

Crossrefs

Cf. A045637 (primes of the form p^2+4, where p is prime).
Cf. A182475 (primes of the form p^2+10, where p is prime).

Programs

  • Mathematica
    mx = 25; Union[Select[Flatten[Table[Prime[a]^2 + Prime[b]^2 - 1, {a, mx}, {b, a, mx}]], # < Prime[mx]^2 && PrimeQ[#] &]] (* T. D. Noe, Mar 29 2013 *)

A243342 Least prime p that is expressible as the sum of three distinct primes squared in exactly n ways.

Original entry on oeis.org

83, 419, 3779, 10739, 240899, 229979, 1180019, 369419, 36964859, 33670379, 13235699, 21899939, 412547339, 370247939, 467152019, 579994619
Offset: 1

Views

Author

Zak Seidov, Jun 03 2014

Keywords

Comments

All terms are congruent to 5 modulo 6 since the first square must be 9.

Examples

			p = 83, {a,b,c} = {3,5,7}, 1 way
p = 419, {a,b,c} = {3,7,19}, {3,11,17}, 2 ways
p = 3779, {a,b,c} ={3,7,61}, {3,17,59}, {3,31,53}, 3 ways
p = 10739, {a,b,c} = {3,11,103}, {3,23,101}, {3,53,89}, {3,67,79}, 4 ways.
		

Crossrefs

Formula

p = a^2 + b^2 + c^2 with a < b < c primes, note that a = 3 in all cases.

A243368 Primes p such that q = p^2 + 10 and q^2 + 10 are also prime.

Original entry on oeis.org

7, 13, 211, 601, 743, 2281, 2659, 2897, 3109, 3361, 4271, 4397, 6173, 7321, 7351, 8807, 8863, 11941, 12377, 13033, 13159, 13999, 14449, 14951, 20117, 20161, 20551, 22709, 24109, 25733, 27299, 27749, 29989, 30071, 31123, 31541, 33347, 33377, 33487, 33629
Offset: 1

Views

Author

Zak Seidov, Jun 04 2014

Keywords

Comments

This is a subsequence of A243367 where both p and p^2 + 10 are terms in A243367, see examples.

Examples

			p = a(1) = 7 = A243367(2) and p^2 + 10 = 59 = A243367(7),
p = a(2) = 13 = A243367(4) and p^2 + 10 = 179 = A243367(15).
		

Crossrefs

Programs

  • PARI
    s=[]; forprime(p=2, 100000, q=p^2+10; if(isprime(q)&&isprime(q^2+10), s=concat(s, p))); s \\ Colin Barker, Jun 04 2014

Extensions

More terms from Colin Barker, Jun 04 2014
Showing 1-5 of 5 results.