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A209310
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Triangular numbers whose sum of triangular divisors is also triangular and greater than 1.
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2
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6, 4186, 32131, 52975, 78210, 111628, 237016, 247456, 584821, 750925, 1464616, 3649051, 5791906, 11297881, 16082956, 24650731, 27243271, 38618866, 46585378, 51546781, 56026405, 76923406, 89880528, 96070591, 126906346, 164629585, 201854278, 228733966
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OFFSET
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1,1
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LINKS
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Donovan Johnson, Table of n, a(n) for n = 1..1000
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EXAMPLE
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4186 is in sequence because it is triangular (4186 = 91*92/2) and the sum of triangular divisors, 4186+91+1 = 4278 is also triangular (4278 = 92*93/2)
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PROG
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(PARI) istriangular(n)=issquare(8*n+1)
{t=0; for(n=1, 10^8, if(istriangular(n), k=sumdiv(n, d, istriangular(d)*d) ; if(istriangular(k)&&k>>1, t+=1; write("b209310.txt", t, " ", n))))}
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CROSSREFS
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Cf. A185027, A035316, A209309.
Sequence in context: A024087 A161845 A317485 * A268504 A099723 A226499
Adjacent sequences: A209307 A209308 A209309 * A209311 A209312 A209313
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KEYWORD
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nonn
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AUTHOR
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Antonio Roldán, Jan 18 2013
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STATUS
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approved
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