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A157870
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a(n) = (4n+1)*(4n+2) = (4n+2)!/(4n)!.
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2
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2, 30, 90, 182, 306, 462, 650, 870, 1122, 1406, 1722, 2070, 2450, 2862, 3306, 3782, 4290, 4830, 5402, 6006, 6642, 7310, 8010, 8742, 9506, 10302, 11130, 11990, 12882, 13806, 14762, 15750, 16770, 17822, 18906, 20022, 21170, 22350, 23562, 24806, 26082, 27390, 28730, 30102, 31506, 32942
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OFFSET
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0,1
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LINKS
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FORMULA
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Sum_{n>=0} 1/a(n) = Pi/8 + log(2)/4.
Sum_{n>=0} (-1)^n/a(n) = ((sqrt(2)-1)*Pi + sqrt(2)*log((2+sqrt(2))/(2-sqrt(2))))/8. (End)
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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SUNKU Sai Swaroop (sai2020(AT)gmail.com), Mar 08 2009
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EXTENSIONS
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Definition corrected and sequence extended by R. J. Mathar, Mar 11 2009
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STATUS
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approved
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