

A324561


Numbers with at least one prime index equal to 0, 1, or 4 modulo 5.


2



2, 4, 6, 7, 8, 10, 11, 12, 13, 14, 16, 18, 20, 21, 22, 23, 24, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 38, 39, 40, 42, 43, 44, 46, 47, 48, 49, 50, 52, 53, 54, 55, 56, 58, 60, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 76, 77, 78, 80, 82, 84, 86, 87
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OFFSET

1,1


COMMENTS

A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
Also Heinz numbers of the integer partitions counted by A039900. The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).


LINKS



EXAMPLE

The sequence of terms together with their prime indices begins:
2: {1}
4: {1,1}
6: {1,2}
7: {4}
8: {1,1,1}
10: {1,3}
11: {5}
12: {1,1,2}
13: {6}
14: {1,4}
16: {1,1,1,1}
18: {1,2,2}
20: {1,1,3}
21: {2,4}
22: {1,5}
23: {9}
24: {1,1,1,2}


MAPLE

with(numtheory):
q:= n> is(irem(pi(min(factorset(n))), 5) in {0, 1, 4}):


MATHEMATICA

Select[Range[100], Intersection[Mod[If[#==1, {}, PrimePi/@First/@FactorInteger[#]], 5], {0, 1, 4}]!={}&]


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



