A318981 Numbers whose prime indices plus 1 are relatively prime.

1, 6, 12, 14, 15, 18, 21, 24, 26, 28, 30, 35, 36, 38, 39, 42, 45, 48, 51, 52, 54, 56, 58, 60, 63, 65, 66, 69, 70, 72, 74, 75, 76, 77, 78, 84, 86, 87, 90, 91, 95, 96, 98, 102, 104, 105, 106, 108, 111, 112, 114, 116, 117, 119, 120, 122, 123, 126, 130, 132, 133

Offset

1,2

Comments

A prime index of n is a number m such that prime(m) divides n.

Links

Table of n, a(n) for n=1..61.

Example

The sequence of integer partitions whose Heinz numbers are in the sequence begins: (), (21), (211), (41), (32), (221), (42), (2111), (61), (411), (321), (43), (2211), (81), (62), (421), (322), (21111).

Mathematica

Select[Range[100], GCD@@(PrimePi/@FactorInteger[#][[All, 1]]+1)==1&]

Crossrefs

Cf. A000837, A007359, A018783, A281116, A289508, A289509, A318978, A318980.

Sequence in context: A336559 A348551 A143957 * A105115 A366532 A325700

Adjacent sequences: A318978 A318979 A318980 * A318982 A318983 A318984

Keyword

nonn

Author

Gus Wiseman, Sep 06 2018

Status

approved