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A155577 Intersection of A154777 and A154778: N = a^2 + 2b^2 = c^2 + 5d^2 for some positive integers a,b,c,d. 1

%I

%S 6,9,24,36,41,54,81,86,89,96,129,134,144,150,164,166,201,214,216,225,

%T 241,246,249,281,294,321,324,326,344,356,369,384,401,409,441,449,454,

%U 486,489,516,521,534,536,566,569,576,600,601,614,641,656,664,681,694

%N Intersection of A154777 and A154778: N = a^2 + 2b^2 = c^2 + 5d^2 for some positive integers a,b,c,d.

%C Subsequence of A155567 (where a,b,c,d may be zero).

%o (PARI) isA155577(n,/* optional 2nd arg allows us to get other sequences */c=[5,2]) = { for(i=1,#c, for(b=1,sqrtint((n-1)\c[i]), issquare(n-c[i]*b^2) & next(2)); return);1}

%o for( n=1,999, isA155577(n) & print1(n","))

%Y Cf. A000404, A154777, A092572, A097268, A154778, A155716, ...

%K easy,nonn

%O 1,1

%A _M. F. Hasler_, Jan 25 2009

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Last modified May 7 09:32 EDT 2021. Contains 343647 sequences. (Running on oeis4.)