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A076305
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Numbers n such that prime(n) + prime(n+1) + prime(n+2) is a square.
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9
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6, 12, 59, 65, 112, 965, 1029, 1455, 1706, 1830, 1890, 2573, 3457, 4490, 4664, 5609, 7927, 9130, 10078, 10143, 12597, 18248, 19727, 20086, 20887, 21708, 22739, 25041, 26536, 28511, 29346, 29664, 29774, 33387, 39945, 40677, 46136, 49869, 58135
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OFFSET
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1,1
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COMMENTS
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See A076304 for the square roots of the sums of the three primes.
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LINKS
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Harvey P. Dale, Table of n, a(n) for n = 1..600
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FORMULA
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a(n) = A000720(A206279(n)). - M. F. Hasler, Jan 03 2020
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EXAMPLE
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6 is in the sequence because prime(6) + prime(7) + prime(8) = 13 + 17 + 19 = 49 = 7^2.
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MATHEMATICA
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Select[Range[60000], IntegerQ[Sqrt[Sum[Prime[k], {k, #, # + 2}]]] &] (* Ray Chandler, Sep 26 2006 *)
Position[Partition[Prime[Range[60000]], 3, 1], _?(IntegerQ[Sqrt[ Total[ #]]]&), 1, Heads->False]//Flatten (* Harvey P. Dale, Sep 28 2018 *)
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PROG
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(PARI) n=0; p=2; q=3; forprime(r=5, 1e9, n++; if(issquare(p+q+r), print1(n", ")); p=q; q=r) \\ Charles R Greathouse IV, Apr 07 2017
(MAGMA) [k:k in [1..60000]| IsSquare(&+[NthPrime(k+m):m in [0, 1, 2]])]; // Marius A. Burtea, Jan 04 2020
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CROSSREFS
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Cf. A076304 (square roots of sums), A080665 (squares = sums), A206279 (lesser of the primes).
Cf. A064397 (same for 2 primes), A072849 (4 primes), A166255 (70 primes), A166261 (120 primes).
Sequence in context: A076722 A322288 A337739 * A088944 A335000 A033931
Adjacent sequences: A076302 A076303 A076304 * A076306 A076307 A076308
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov, Oct 05 2002
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EXTENSIONS
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Corrected by Ray Chandler, Sep 26 2006
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STATUS
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approved
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