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 1-3 of 3 results.

A098561 Numbers n such that the sum of the squares of the first n primes is prime.

Original entry on oeis.org

2, 18, 26, 36, 68, 78, 144, 158, 164, 174, 192, 212, 216, 236, 264, 288, 294, 338, 344, 356, 384, 404, 416, 426, 500, 516, 518, 522, 534, 540, 548, 614, 678, 680, 782, 858, 866, 876, 878, 896, 900, 912, 950, 974, 996, 1064, 1080, 1082, 1100, 1122, 1158, 1160
Offset: 1

Views

Author

Rick L. Shepherd, Sep 14 2004

Keywords

Comments

a(n) must clearly be even.

Examples

			2 is a term as the sum of the squares of the first two primes is 2^2 + 3^2 = 13, which is prime.
		

Crossrefs

Cf. A098562 (corresponding primes), A024450 (sums of squares of primes), A098563 (sums of cubes of primes), A013916 (sums of primes).

Programs

  • Mathematica
    Select[Range[1000], PrimeQ[Sum[Prime[i]^2, {i, #}]] &] (* Carl Najafi, Aug 22 2011 *)

A140250 a(n) is the largest cube <= A066525(n).

Original entry on oeis.org

343, 15625, 34965783, 106496424, 3023464536, 3659383421, 7222633237, 10403062487, 11179320256, 11993263569, 25881801912, 36495256013, 40672093519, 47516597848, 49917330568, 63616767488, 84200449887, 96323848704, 573234910443, 972947676429
Offset: 1

Views

Author

Enoch Haga, May 15 2008

Keywords

Comments

Suggested by Carlos Rivera's Prime Puzzles & Problems Connection, Puzzle 443 (which asks if a sum of consecutive cubes can be a cube or a prime cube).

Examples

			In A066525 the first term is 503, the sum of cubes of the first four consecutive primes, 2 3 5 7. The cube just less than 503 is 343, a(1) in this sequence.
		

Crossrefs

Programs

  • Maple
    with(numtheory): P:=proc(n) add(ithprime(k)^3,k=1..n): end:
    A098563 := proc(n)local m: option remember: if(n=0)then return 0: fi: m:=procname(n-1)+2: while true do if(isprime(P(m)))then return m:fi: m:=m+2:od: end:
    A140250 := proc(n)return floor(surd(P(A098563(n)),3))^3: end:
    seq(A140250(n),n=1..20); # Nathaniel Johnston, Apr 21 2011
  • Mathematica
    Floor[CubeRoot[#]]^3&/@Select[Accumulate[Prime[Range[400]]^3],PrimeQ] (* Harvey P. Dale, May 22 2023 *)

Extensions

Edited by N. J. A. Sloane, Aug 25 2008
a(11)-a(20) from Nathaniel Johnston, Apr 21 2011

A140251 Smallest cubes > terms in A066525.

Original entry on oeis.org

512, 17576, 35287552, 107171875, 3029741623, 3666512088, 7233848504, 10417365504, 11194326053, 12008989000, 25908060079, 36528273432, 40707584000, 47555965367, 49958012987, 63664587657, 84258095104, 96386901625, 573441954112, 973242271000
Offset: 1

Views

Author

Enoch Haga, May 15 2008

Keywords

Examples

			The cube just greater than 503 is 512; a(1) in this sequence.
		

References

  • Suggested by Carlos Rivera's Prime Puzzles & Problems Connection, Puzzle 443 (which asks if the SCCP can be a cube or a prime cube).

Crossrefs

Formula

For each of the terms in A066525 (which are SCCP, sums of cubes of consecutive primes), find the cube just exceeding the term.

Extensions

a(11)-a(20) from Nathaniel Johnston, Apr 21 2011
Showing 1-3 of 3 results.