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A214515 Numbers of the form p^2 + q^2 + r^2 + s^2, where p, q, r, and s are primes. 4
16, 21, 26, 31, 36, 37, 42, 47, 52, 58, 61, 63, 66, 68, 71, 76, 79, 82, 84, 87, 92, 100, 103, 106, 108, 111, 116, 124, 127, 132, 133, 138, 143, 148, 151, 154, 156, 159, 164, 172, 175, 178, 180, 181, 183, 186, 188, 191, 196, 199, 202, 204, 207, 212, 220, 223 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

MATHEMATICA

nn = 10^3; ps = Prime[Range[PrimePi[Sqrt[nn]]]]; t = Flatten[Table[ps[[i]]^2 + ps[[j]]^2 + ps[[k]]^2 + ps[[l]]^2, {i, Length[ps]}, {j, i, Length[ps]}, {k, j, Length[ps]}, {l, k, Length[ps]}]]; t = Select[t, # <= nn &]; Union[t]

CROSSREFS

Cf. A045636 (two primes), A214514 (three primes).

Sequence in context: A180411 A050436 A038868 * A270783 A330591 A302167

Adjacent sequences:  A214512 A214513 A214514 * A214516 A214517 A214518

KEYWORD

nonn

AUTHOR

T. D. Noe, Jul 29 2012

STATUS

approved

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Last modified August 15 09:19 EDT 2022. Contains 356135 sequences. (Running on oeis4.)