A318992 Numbers whose consecutive prime indices are not all divisible.

15, 30, 33, 35, 45, 51, 55, 60, 66, 69, 70, 75, 77, 85, 90, 91, 93, 95, 99, 102, 105, 110, 119, 120, 123, 132, 135, 138, 140, 141, 143, 145, 150, 153, 154, 155, 161, 165, 170, 175, 177, 180, 182, 186, 187, 190, 195, 198, 201, 203, 204, 205, 207, 209, 210, 215

Offset: 1

Author

Gus Wiseman, Sep 06 2018

Keywords

• nonn

Examples

			The sequence of partitions whose Heinz numbers belong to the sequence begins: (3,2), (3,2,1), (5,2), (4,3), (3,2,2), (7,2), (5,3), (3,2,1,1), (5,2,1), (9,2), (4,3,1), (3,3,2), (5,4), (7,3), (3,2,2,1), (6,4), (11,2), (8,3), (5,2,2).
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A001221, A001222, A008480, A289509, A300912, A318990, A318991, A318993.

Programs

Mathematica

Select[Range[100],!Or[#==1,PrimePowerQ[#],Divisible@@Reverse[PrimePi/@FactorInteger[#][[All,1]]]]&]

PARI

ok(n)={my(v=apply(primepi, factor(n)[,1])); for(i=2, #v, if(v[i]%v[i-1], return(1))); 0} \\ Andrew Howroyd, Oct 26 2018