A188112 - OEIS

A188112

Integers of the form x^2+xy+2y^2,with x and y nonnegative, with repetitions.

0, 1, 2, 4, 4, 8, 8, 9, 11, 14, 16, 16, 18, 22, 22, 23, 25, 28, 32, 32, 32, 36, 36, 37, 43, 44, 44, 46, 49, 50, 53, 56, 56, 58, 58, 64, 64, 64, 71, 72, 72, 74, 74, 77, 79, 81, 86, 88, 88, 88, 92, 92, 98, 99, 100, 100, 106, 106, 107, 109, 112, 112, 116, 116, 121, 126, 127

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OFFSET

1,3

COMMENTS

Primes appear only once.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

EXAMPLE

{n,x,y}: {0,0,0},...,{4,1,1},{4,2,0},{8,0,2},{8,2,1},...,{11,1,2},{14,3,1}.

MATHEMATICA

f[upto_]:=Module[{max=Floor[Sqrt[upto]], s}, s=Sort[First[#]^2+ Times@@#+2Last[#]^2&/@Tuples[Range[0, max], {2}]]; Select[s, #<=upto&]]; f[150] (* Harvey P. Dale, Mar 28 2011 *)

CROSSREFS

Cf. A106856, primes of the form x^2+xy+2y^2, with x and y nonnegative.

Sequence in context: A207872 A140513 A265322 * A333194 A349131 A366665

Adjacent sequences: A188109 A188110 A188111 * A188113 A188114 A188115

KEYWORD

nonn,easy

AUTHOR

Zak Seidov, Mar 21 2011

STATUS

approved