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A255200
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Numbers n such that triangular numbers T(n), T(n+1) and T(n+2) are 3-almost primes.
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2
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17, 28, 41, 281, 2081, 2801, 4721, 5441, 6196, 12161, 12916, 13996, 20476, 24916, 32321, 32441, 34156, 34961, 40036, 56596, 70996, 73361, 94396
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OFFSET
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1,1
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COMMENTS
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Numbers n such that n, n+1 and n+2 are terms in A108815.
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LINKS
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EXAMPLE
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PROG
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(PARI) issemi(n)=bigomega(n)==2
is(n)=if(n%2, if(n%4==1, isprime((n+3)/4) && isprime(n+2) && isprime(n) && issemi((n+1)/2), isprime((n+1)/4) && isprime(n) && isprime(n+2) && issemi((n+3)/2)), if(n%4==2, isprime((n+2)/4) && isprime(n+1) && isprime(n+3) && issemi(n/2), isprime(n/4) && isprime(n+1) && isprime(n+3) && issemi(n/2+1))) \\ Charles R Greathouse IV, Feb 05 2017
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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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