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A177964
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Indices m for which A177961(m) = 4.
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3
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2, 13, 17, 28, 32, 43, 47, 58, 62, 73, 77, 88, 92, 103, 107, 118, 122, 133, 137, 148, 152, 163, 167, 178, 182, 193, 197, 208, 212, 223, 227, 238, 242, 253, 257, 268, 272, 283, 287, 298, 302, 313, 317, 328, 332, 343, 347, 358, 362, 373, 377, 388, 392, 403, 407, 418, 422
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OFFSET
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1,1
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COMMENTS
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Note that 4 is the smallest value of A177961.
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LINKS
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FORMULA
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a(n+2) = a(n)+15.
a(n) == (-1)^n (mod 3).
Sum_{n>=1} (-1)^(n+1)/a(n) = tan(3*Pi/10)*Pi/15 = sqrt(1+2/sqrt(5))*Pi/15. - Amiram Eldar, Feb 28 2023
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MAPLE
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seq(seq(15*i+j, j=[2, 13]), i=0..100); # Robert Israel, Jul 31 2015
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MATHEMATICA
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LinearRecurrence[{1, 1, -1}, {2, 13, 17}, 80] (* Harvey P. Dale, Nov 01 2023 *)
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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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EXTENSIONS
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STATUS
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approved
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