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A270475
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Integers n such that A003266(n) is not divisible by n*(n+1)/2.
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1
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2, 3, 4, 6, 7, 22, 23, 42, 43, 66, 67, 82, 83, 102, 103, 126, 127, 162, 163, 166, 167, 222, 223, 226, 227, 282, 283, 366, 367, 382, 383, 442, 443, 462, 463, 466, 467, 486, 487, 502, 503, 522, 523, 546, 547, 586, 587, 606, 607, 642, 643, 646, 647, 682, 683, 726, 727, 786, 787
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OFFSET
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1,1
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COMMENTS
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This sequence contains primes dividing all Fibonacci sequences.
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LINKS
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EXAMPLE
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6 is a term because (1*1*2*3*5*8) is not divisible by (1+2+3+4+5+6).
5 is not a term because (1*1*2*3*5) is divisible by (1+2+3+4+5).
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MATHEMATICA
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nn = 800; Function[k, Select[Range@ nn, ! Divisible[k[[#]], # (# + 1)/2] &]]@ FoldList[Times, Array[Fibonacci@ # &, nn]] (* Michael De Vlieger, Mar 19 2016 *)
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PROG
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(PARI) a(n) = prod(k=1, n, fibonacci(k));
for(n=1, 1e3, if(a(n) % (n*(n+1)/2) != 0, print1(n, ", ")));
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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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