A380295 Numbers that can be written as a^2 + 3*b^2 for some a, b in A155716 and also as c^2 + 6*d^2 for some c, d in A092572.
1552, 1975, 4753, 5047, 5425, 7825, 8167, 9175, 10096, 11025, 11536, 12007, 16528, 16807, 16993, 18823, 19600, 23863, 24832, 25633, 25767, 26983, 27223, 29200, 30919, 31600, 31927, 32791, 33175, 35329, 35623, 41953, 43063, 43687, 51943, 54775, 57303, 59575, 60016, 61783, 63175, 71575, 72103
Offset: 1
Keywords
Examples
a(5) = 5425 is a term because 5425 = 73^2 + 6 * 4^2 = 25^2 + 3 * 40^2 with 73 = 5^2 + 3 * 4^2, 4 = 1^2 + 3 * 1^2, 25 = 1^2 + 6 * 2^2 and 40 = 4^2 + 6 * 2^2.
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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Maple
N:= 500: # for terms <= N^2 A:= {seq(seq(a^2 + 3*b^2,a=1..floor(sqrt(N-3*b^2))),b=1..floor(sqrt(N/3)))}: B:= {seq(seq(a^2 + 6*b^2,a=1..floor(sqrt(N-6*b^2))),b=1..floor(sqrt(N/6)))}: C:= select(`<=`,{seq(seq(a^2+6*b^2,a=A),b=A)},N^2): E:= select(`<=`,{seq(seq(a^2+3*b^2,a=B),b=B)},N^2): sort(convert(C intersect E,list));
Comments