login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A302797 Squarefree numbers whose prime indices are pairwise coprime. Heinz numbers of strict integer partitions with pairwise coprime parts. 13
1, 2, 6, 10, 14, 15, 22, 26, 30, 33, 34, 35, 38, 46, 51, 55, 58, 62, 66, 69, 70, 74, 77, 82, 85, 86, 93, 94, 95, 102, 106, 110, 118, 119, 122, 123, 134, 138, 141, 142, 143, 145, 146, 154, 155, 158, 161, 165, 166, 170, 177, 178, 186, 187, 190, 194, 201, 202 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A prime index of n is a number m such that prime(m) divides n. Two or more numbers are coprime if no pair of them has a common divisor other than 1. A single number is not considered coprime unless it is equal to 1.

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

LINKS

Table of n, a(n) for n=1..58.

EXAMPLE

Sequence of terms together with their sets of prime indices begins:

01 : {}

02 : {1}

06 : {1,2}

10 : {1,3}

14 : {1,4}

15 : {2,3}

22 : {1,5}

26 : {1,6}

30 : {1,2,3}

33 : {2,5}

34 : {1,7}

35 : {3,4}

38 : {1,8}

46 : {1,9}

51 : {2,7}

55 : {3,5}

58 : {1,10}

62 : {1,11}

66 : {1,2,5}

69 : {2,9}

70 : {1,3,4}

MATHEMATICA

Select[Range[100], Or[#===1, SquareFreeQ[#]&&CoprimeQ@@PrimePi/@FactorInteger[#][[All, 1]]]&]

CROSSREFS

Cf. A001222, A003963, A005117, A007359, A051424, A056239, A275024, A289509, A302242, A302505, A302696, A302697, A302698, A302796, A302798.

Sequence in context: A080324 A165562 A302796 * A130319 A191256 A067368

Adjacent sequences:  A302794 A302795 A302796 * A302798 A302799 A302800

KEYWORD

nonn

AUTHOR

Gus Wiseman, Apr 13 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 28 03:28 EST 2020. Contains 331314 sequences. (Running on oeis4.)