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A280014
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Numbers m == +- 2 (mod 10) but not m == 2 (mod 6).
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1
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12, 18, 22, 28, 42, 48, 52, 58, 72, 78, 82, 88, 102, 108, 112, 118, 132, 138, 142, 148, 162, 168, 172, 178, 192, 198, 202, 208, 222, 228, 232, 238, 252, 258, 262, 268, 282, 288, 292, 298, 312, 318, 322, 328, 342, 348, 352, 358, 372, 378, 382, 388, 402, 408, 412, 418, 432, 438, 442, 448, 462, 468, 472, 478, 492, 498, 502, 508, 522
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OFFSET
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1,1
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COMMENTS
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Also, numbers congruent to 12, 18, 22 or 28 (mod 30). Also, numbers such that A056619(n) = 5.
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LINKS
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FORMULA
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a(n+4) = a(n)+30.
G.f.: 2*x*(2 + x)*(3 + x^2 + x^3) / ((1 - x)^2*(1 + x)*(1 + x^2)).
a(n) = a(n-1) + a(n-4) - a(n-5) for n>5.
(End)
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MATHEMATICA
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Select[Range@ 524, MemberQ[{12, 18, 22, 28}, Mod[#, 30]] &] (* Michael De Vlieger, Feb 21 2017 *)
LinearRecurrence[{1, 0, 0, 1, -1}, {12, 18, 22, 28, 42}, 80] (* Harvey P. Dale, Nov 09 2017 *)
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PROG
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(PARI) a(n)=[12, 18, 22, 28][(n-1)%4+1]+(n-1)\4*30
(PARI) Vec(2*x*(2 + x)*(3 + x^2 + x^3) / ((1 - x)^2*(1 + x)*(1 + x^2)) + O(x^60)) \\ Colin Barker, Feb 12 2018
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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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STATUS
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approved
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