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%I #22 Sep 19 2013 23:56:03
%S 2,10,24,43,68,98,133,174,221,273,330,393,461,535,614,699,789,885,986,
%T 1092,1204,1322,1445,1573,1707,1846,1991,2141,2297,2458,2625,2797,
%U 2975,3158,3346,3540,3740,3945,4155,4371,4592,4819,5051,5289,5532,5781,6035,6294
%N Surface area of Johnson square pyramid (rounded down) with all the edge-lengths equal to n.
%C Johnson square pyramid: a square base with four equilateral triangular-faces. All the edge-lengths are equal.
%H K. D. Bajpai, <a href="/A224837/b224837.txt">Table of n, a(n) for n = 1..1000</a>
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Square_pyramid">Square pyramid</a>
%F a(n) = floor((1+sqrt(3))*n^2).
%e a(3)=24: Surface area = (1+sqrt(3))*k^2 = (1+sqrt(3))*3^2 = 24.58845727 and floor(24.58845727) = 24.
%p KD:= proc() local a,b; a:=evalf(1+sqrt(3))*k^2; b:=floor(a); RETURN(b): end: seq(KD(),k=1..100);
%t Table[Floor[(1+Sqrt[3])*k^2], {k, 500}]
%o (PARI) vector(500, k, floor((1+sqrt(3))*k^2))
%o (PARI) a(n)=n^2+sqrtint(3*n^4) \\ _Charles R Greathouse IV_, Sep 18 2013
%Y Cf. A090388, A228189.
%K nonn
%O 1,1
%A _K. D. Bajpai_, Sep 18 2013
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