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A069174
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Centered 23-gonal numbers.
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5
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1, 24, 70, 139, 231, 346, 484, 645, 829, 1036, 1266, 1519, 1795, 2094, 2416, 2761, 3129, 3520, 3934, 4371, 4831, 5314, 5820, 6349, 6901, 7476, 8074, 8695, 9339, 10006
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = (23*n^2 - 23*n + 2)/2.
Sum_{n>=1} 1/a(n) = 2*Pi*tan(sqrt(15/23)*Pi/2)/sqrt(345).
Sum_{n>=1} a(n)/n! = 25*e/2 - 1.
Sum_{n>=1} (-1)^n * a(n)/n! = 25/(2*e) - 1. (End)
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MATHEMATICA
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PROG
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CROSSREFS
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Cf. centered polygonal numbers listed in A069190.
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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