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editing

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Terrence Terence Tao, <a href="http://terrytao.wordpress.com/2013/07/07/the-distribution-of-primes-in-doubly-densely-divisible-moduli/">The distribution of primes in doubly densely divisible moduli</a>

approved

editing

reviewed

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reviewed

editing

proposed

Terrence Tao, <a href="http://terrytao.wordpress.com/2013/07/07/the-distribution-of-primes-in-doubly-densely-divisible-moduli/">The distribution of primes in doubly densely divisible moduli</a>

Terrence Tao, <a href="http://terrytao.wordpress.com/2013/07/07/the-distribution-of-primes-in-doubly-densely-divisible-moduli/">The distribution of primes in doubly densely divisible moduli</a>

allocated for Charles R Greathouse IV

Doubly 3-densely divisible numbers.

1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 20, 24, 27, 30, 32, 36, 40, 45, 48, 54, 60, 63, 64, 72, 80, 81, 84, 90, 96, 100, 108, 112, 120, 126, 128, 135, 140, 144, 150, 160, 162, 168, 176, 180, 189, 192, 200, 210, 216, 220, 224, 225, 240, 243, 252, 256, 264, 270, 280, 288, 300, 315

1,2

Numbers n such that for each d | n, there is some 3-densely divisible (A196149) number d' such that d/3 < d' <= d.

Terrence Tao, <a href="http://terrytao.wordpress.com/2013/07/07/the-distribution-of-primes-in-doubly-densely-divisible-moduli/">The distribution of primes in doubly densely divisible moduli</a>

Charles R Greathouse IV, <a href="/A227731/b227731.txt">Table of n, a(n) for n = 1..10000</a>

(PARI) dense(n, k)=my(d=divisors(n)); for(i=2, #d, if(d[i]>k*d[i-1], return(0))); 1

is(n)=my(d=select(k->dense(k, 3), divisors(n))); if(!#d||3*d[#d]<n, return(0)); for(i=2, #d, if(d[i]>3*d[i-1], return(0))); 1

Cf. A227730, A196149.

allocated

nonn

Charles R Greathouse IV, Jul 23 2013

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editing

allocated for Charles R Greathouse IV

allocated

approved