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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A133940 Numbers n such that (prime(n)^2 + prime(n+1)^2 + prime(n+2)^2)/3 is prime (A084951).

Original entry on oeis.org

4, 5, 8, 13, 15, 26, 46, 47, 50, 55, 57, 59, 61, 65, 66, 69, 77, 82, 89, 91, 94, 101, 105, 116, 134, 136, 137, 138, 144, 157, 194, 216, 219, 221, 224, 225, 229, 230, 234, 249, 257, 261, 263, 271, 272, 275, 306, 316, 319, 323
Offset: 1

Views

Author

Artur Jasinski, Sep 30 2007

Keywords

Comments

With the exception of the first two terms, all numbers in A133529 are divisible by 3.

Examples

			a(1)=4 because (prime(4)^2 + prime(5)^2 + prime(6)^2)/3 = 113 is prime.
		

Crossrefs

Programs

  • Maple
    select(n -> isprime((ithprime(n)^2 + ithprime(n+1)^2 + ithprime(n+2)^2)/3), [$3 .. 1000]); # Robert Israel, Apr 21 2015
  • Mathematica
    b = {}; a = 2; Do[k = (Prime[n]^a + Prime[n + 1]^a + Prime[n + 2]^a)/3; If[PrimeQ[k], AppendTo[b, n]], {n, 1, 200}]; b
  • PARI
    is(n)=my(p=prime(n),q=nextprime(p+1),r=nextprime(q+1)); n>3 && isprime((p^2+q^2+r^2)/3) \\ Charles R Greathouse IV, Apr 21 2015

Extensions

Corrected and edited by Zak Seidov, Apr 21 2015

A259772 Primes p such that p^3 + q^2 + r is also prime, where p,q,r are consecutive primes.

Original entry on oeis.org

3, 17, 19, 43, 53, 89, 107, 149, 293, 401, 439, 449, 659, 809, 821, 937, 1009, 1031, 1091, 1097, 1123, 1163, 1181, 1259, 1277, 1367, 1427, 1657, 1721, 1777, 1789, 1811, 1987, 2027, 2063, 2207, 2333, 2417, 2503, 2657, 2713, 3067, 3079, 3083, 3251, 3389, 3491, 3527
Offset: 1

Views

Author

K. D. Bajpai, Jul 05 2015

Keywords

Examples

			a(2) = 17 is prime: 17^3 + 19^2 + 23 = 5297 which is also prime.
a(3) = 19 is prime: 19^3 + 23^2 + 29 = 7417 which is also prime.
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo (3000) | IsPrime(k) where k is (p^3 + NextPrime(p)^2 + NextPrime(NextPrime(p)))];
  • Maple
    select(n -> isprime(n) and isprime((n)^3+nextprime(n)^2+nextprime(nextprime((n)))), [seq(n, n=1..10000)]);
  • Mathematica
    Select[Prime[Range[1000]], PrimeQ[#^3 + NextPrime[#]^2 + NextPrime[NextPrime[#]]]&]
    Select[Partition[Prime[Range[500]],3,1],PrimeQ[#[[1]]^3+ #[[2]]^2+ #[[3]]]&][[All,1]] (* Harvey P. Dale, Dec 23 2021 *)
  • PARI
    forprime(p=1, 3000, q=nextprime(p+1); r=nextprime(q+1); k=(p^3 + q^2 + r); if(isprime(k), print1(p,", ")))
    

A131686 Sum of squares of five consecutive primes.

Original entry on oeis.org

208, 373, 653, 989, 1469, 2189, 2981, 4061, 5381, 6701, 8069, 9917, 12029, 14069, 16709, 19541, 22061, 24821, 27989, 31421, 35789, 40661, 45029, 49589, 53549, 56909, 62837, 69389, 76709, 84149, 93581, 100253, 107741, 115541, 124109, 131837
Offset: 1

Views

Author

Artur Jasinski, Sep 14 2007

Keywords

Examples

			a(1)=208 because 2^2+3^2+5^2+7^2+11^2=208
		

Crossrefs

Programs

  • Mathematica
    a = 2; Table[Prime[n]^a + Prime[n + 1]^a + Prime[n + 2]^a + Prime[n + 3]^a + Prime[n + 4]^a, {n, 1, 100}]

A133562 Numbers which are the sum of the squares of seven consecutive primes.

Original entry on oeis.org

666, 1023, 1543, 2359, 3271, 4519, 6031, 7591, 9439, 11719, 14359, 17119, 20239, 23599, 27079, 31111, 35191, 39631, 45319, 51031, 56599, 62719, 68359, 74239, 82447, 90199, 98767, 107479, 118231, 129151, 141031, 151471, 162199, 173359
Offset: 1

Views

Author

Artur Jasinski, Sep 16 2007

Keywords

Comments

For primes in this sequence see A133560.
For sum of squares of two consecutive primes only 2^2 + 3^2 = 13 is prime.
For sum of squares of three consecutive primes A133529 it seems that only 83 is a prime (checked for all n < 1000000).
Sums of squares of four (and all even number) of consecutive primes are even numbers with exception n=1 but 2^2 + 3^2 + 5^2 + 7^2 = 87 = 3*29 is not prime.
For primes that are sums of squares of five consecutive primes see A133559.

Examples

			a(6) = 13^2 + 17^2 + 19^2 + 23^2 + 29^2 + 31^2 + 37^2 = 4519.
		

Crossrefs

Programs

  • Maple
    seq(add(ithprime(n+k)^2,k=0..6),n=1..35); # Muniru A Asiru, Jul 08 2018
  • Mathematica
    b = {}; a = 2; Do[k = Prime[n]^a + Prime[n + 1]^a + Prime[n + 2]^a + Prime[n + 3]^a + Prime[n + 4]^a + Prime[n + 5]^a + Prime[n + 6]^a; AppendTo[b, k], {n, 1, 100}]; b
    Total/@Partition[Prime[Range[40]]^2,7,1] (* Harvey P. Dale, Jan 01 2025 *)

Extensions

Edited by Michel Marcus, Jul 08 2018

A242218 Semiprimes which are the arithmetic mean of three consecutive primes.

Original entry on oeis.org

511, 537, 1073, 1461, 1501, 1541, 1763, 2071, 2181, 2449, 4101, 4387, 4399, 4467, 4559, 4607, 4681, 4705, 5089, 5257, 5429, 6415, 6621, 6671, 7097, 7111, 7261, 7391, 7447, 7811, 7831, 7897, 7909, 7969, 8079, 8129, 8193, 8333, 8639, 8915, 9101, 9113, 9123, 9211
Offset: 1

Views

Author

K. D. Bajpai, May 07 2014

Keywords

Examples

			a(1) = 511 = (503 + 509 + 521)/3 = 7 * 73 is semiprime.
a(2) = 537 = (523 + 541 + 547)/3 = 3 * 179 is semiprime.
		

Crossrefs

Programs

  • Maple
    with(numtheory): A242218:= proc()local k ; k:=(ithprime(x)+ithprime(x+1)+ithprime(x+2))/3; if k=floor(k) and bigomega(k)=2 then RETURN (k);  fi; end: seq(A242218 (),x=2..2000);
  • PARI
    for(k=1, 2000, t=prime(k)+prime(k+1)+prime(k+2); if(t%3==0 && bigomega(t/3)==2, print1(t/3, ", "))) \\ Colin Barker, May 08 2014

A258269 Primes of the form p^3 + q^2 + r, where p, q, r are consecutive primes.

Original entry on oeis.org

59, 5297, 7417, 81769, 152419, 714479, 1237037, 3330907, 25248317, 64648901, 84801217, 90728159, 286628773, 530133671, 554065817, 823543381, 1028270917, 1096980919, 1299792317, 1321357391, 1417523659, 1574410169, 1648622903, 1997248987, 2084078057, 2556384373
Offset: 1

Views

Author

K. D. Bajpai, May 25 2015

Keywords

Examples

			a(1) = 59 is prime of the form 3^3 + 5^2 + 7.
a(2) = 5297 is prime of the form 17^3 + 19^2 + 23.
		

Crossrefs

Programs

  • Magma
    [k: p in PrimesUpTo (3000) | IsPrime(k) where k is (p^3 + NextPrime(p)^2 + NextPrime(NextPrime(p)))];
    
  • Maple
    A258269:= n-> (ithprime(n)^3+ithprime(n+1)^2+ithprime(n+2)): select(isprime, [seq((A258269(n), n=1..5000))]);
  • Mathematica
    Select[Table[p = Prime[n]; q = NextPrime[p]; r = NextPrime[q]; p^3 + q^2 + r, {n, 5000}], PrimeQ]
  • PARI
    forprime(p=1, 5000, q=nextprime(p+1); r=nextprime(q+1);  k=(p^3 + q^2 + r); if(isprime(k), print1(k,", ")))

A164130 Sums s of squares of three consecutive primes, such that s-+2 are primes.

Original entry on oeis.org

195, 5739, 18459, 32259, 33939, 60291, 74019, 169491, 187131, 244899, 276819, 388179, 783531, 902139, 3588339, 5041491, 5145819, 5193051, 8687091, 9637491, 10227291, 10910019, 11341491, 11757339, 14834379, 15354651, 16115091
Offset: 1

Views

Author

Keywords

Examples

			5^2 + 7^2 + 11^2 = 195 is a sum of the squared consecutive primes 5, 7 and 11, and 193 and 197 are primes, so 195 is a member of the sequence.
		

Crossrefs

Programs

  • Maple
    q:= 2: r:= 3: R:= NULL: count:= 0:
    while count < 100 do
      p:= q; q:= r; r:= nextprime(r);
      s:= p^2+q^2+r^2;
      if isprime(s-2) and isprime(s+2) then
        count:= count+1; R:= R,s;
      fi;
    od:
    R; # Robert Israel, Apr 21 2023
  • Mathematica
    lst={};Do[p=Prime[n]^2+Prime[n+1]^2+Prime[n+2]^2;If[PrimeQ[p-2]&&PrimeQ[p+2], AppendTo[lst,p]],{n,8!}];lst

Formula

A133529 INTERSECT A087679. - R. J. Mathar, Aug 27 2009

Extensions

Comment turned into example by R. J. Mathar, Aug 27 2009

A242209 Semiprimes sp = p^2 + q^2 + r^2 where p, q and r are consecutive primes.

Original entry on oeis.org

38, 339, 579, 1731, 5739, 8499, 32259, 133851, 145779, 163851, 207579, 222531, 235779, 260187, 308019, 323619, 366819, 469731, 550491, 644979, 684699, 743091, 926427, 1003539, 1242939, 1743531, 1808259, 1852107, 1909059, 2075091, 2585571, 4226979, 5358291
Offset: 1

Views

Author

K. D. Bajpai, May 07 2014

Keywords

Comments

Subsequence of A133529.
All the terms in the sequence, except a(1), are divisible by 3.

Examples

			a(1) = 38 = 2^2 + 3^2 + 5^2 = 2*19 is semiprime.
a(2) = 339 = 7^2 + 11^2 + 13^2 = 3*113 is semiprime.
		

Crossrefs

Programs

  • Maple
    with(numtheory): A242209:= proc()local k ; k:=(ithprime(x)^2+ithprime(x+1)^2+ithprime(x+2)^2); if bigomega(k)=2 then RETURN (k); fi;end: seq(A242209 (),x=1..500);
  • Mathematica
    Select[Total[#^2]&/@Partition[Prime[Range[300]],3,1],PrimeOmega[#]==2&] (* Harvey P. Dale, Nov 05 2015 *)
  • PARI
    for(k=1, 500, sp=prime(k)^2+prime(k+1)^2+prime(k+2)^2; if(bigomega(sp)==2, print1(sp, ", "))) \\ Colin Barker, May 07 2014

A129592 The smallest in a triple of three consecutive primes such that the ceiling of the square root of their sums-of-squares is prime.

Original entry on oeis.org

2, 7, 13, 43, 53, 59, 127, 241, 271, 317, 331, 349, 367, 439, 487, 491, 607, 659, 719, 733, 757, 773, 821, 857, 881, 929, 971, 1087, 1193, 1259, 1289, 1303, 1409, 1427, 1453, 1607, 1663, 1693, 1723, 1747, 1789, 1949, 2053, 2087, 2089, 2131, 2251, 2333, 2393, 2467, 2549, 2633, 2671, 2719
Offset: 1

Views

Author

J. M. Bergot, May 30 2007

Keywords

Comments

Can three squares with consecutive prime sides prime(i), i=k,...,k+2, be contained/morphed in a larger square also with prime sides just slightly greater than required?
The areas are the squares of the prime sides; the total area is their sum prime(k)^2 + prime(k+1)^2 + prime(k+2)^2, and pulling the square root is the diagonal of the hosting square. The sequence lists the first, prime(k), if this diagonal (rounded up) is a prime number, indicating that a rather tight enclosing square with (again) a prime side length can be found.

Examples

			Take 13,17,19 with summed squares 169 + 289 + 361 = 819 = A133529(6). The square root is approximately 28.6 and rounding up to 29 yields a prime, so 13 is a term.
		

Programs

  • Mathematica
    Select[Partition[Prime[Range[400]],3,1],PrimeQ[Ceiling[ Sqrt[ Total[ #^2]]]]&][[All,1]] (* Harvey P. Dale, Feb 05 2019 *)

Formula

{A000040(n): ceiling(sqrt(A133529(n))) in A000040}. - R. J. Mathar, Jul 10 2011

Extensions

Edited and extended by R. J. Mathar, Jul 10 2011

A133557 Numbers k for which the sum of squares of five consecutive primes starting with prime(k) is prime (A133559).

Original entry on oeis.org

2, 3, 9, 10, 11, 16, 18, 25, 26, 28, 31, 33, 36, 42, 43, 46, 47, 54, 56, 58, 63, 68, 76, 87, 91, 93, 99, 101, 105, 106, 114, 127, 131, 145, 153, 159, 183, 186, 196, 201, 206, 229, 230, 232, 233, 238, 239, 241, 244, 245, 246, 248, 253, 256, 257, 264, 265, 266, 268
Offset: 1

Views

Author

Artur Jasinski, Sep 16 2007

Keywords

Comments

For sums of squares of two consecutive primes, only k=1 yields a prime.
For sums of squares of three consecutive primes A133529, it seems that only k=2 yields a prime (checked for all k < 1000000).
Sums of squares of four (and all even numbers of) consecutive primes are even numbers except at k=1.

Examples

			a(1)=2 because prime(2)^2 + prime(3)^2 + prime(4)^2 + prime(5)^2 + prime(6)^2 = 3^2 + 5^2 + 7^2 + 11^2 + 13^2 = 373 is prime.
		

Crossrefs

Programs

  • Mathematica
    b = {}; a = 2; Do[k = Prime[n]^a + Prime[n + 1]^a + Prime[n + 2]^a + Prime[n + 3]^a + Prime[n + 4]^a; If[PrimeQ[k], AppendTo[b, n]], {n, 1, 100}]; b (* Artur Jasinski *)

Extensions

Name and example corrected by Jonathan Sondow, Nov 04 2015
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