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A182084
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3*n - n/p, where p is the smallest prime dividing n.
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0
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5, 8, 10, 14, 15, 20, 20, 24, 25, 32, 30, 38, 35, 40, 40, 50, 45, 56, 50, 56, 55, 68, 60, 70, 65, 72, 70, 86, 75, 92, 80, 88, 85, 98, 90, 110, 95, 104, 100, 122, 105, 128, 110, 120, 115, 140, 120, 140, 125, 136, 130, 158, 135, 154, 140, 152, 145, 176, 150, 182, 155, 168, 160, 182, 165, 200, 170, 184, 175, 212, 180, 218, 185, 200, 190, 220, 195, 236, 200
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OFFSET
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2,1
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COMMENTS
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Conjectured to be minimal number of nodes in any non-bipartite regular graph of degree n, diameter 2 and girth 4.
(5/2)*n<=a(n)<=3*n-1, the lower limit corresponds to even n's, the upper limit to odd prime n's. - Zak Seidov, Apr 13 2012
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REFERENCES
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Sheehan, J. An extremal problem in finite graph theory. In Infinite and finite sets (Colloq., Keszthely, 1973; dedicated to P. Erdős on his 60th birthday), Vol. III, pp. 1235--1239. Colloq. Math. Soc. Janos Bolyai, Vol. 10, North-Holland, Amsterdam, 1975. MR0376429 (51 #12604)
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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