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A324856 Numbers divisible by exactly one of their prime indices. 9
2, 10, 14, 15, 22, 26, 34, 38, 45, 46, 50, 55, 58, 62, 70, 74, 82, 86, 94, 98, 105, 106, 118, 119, 122, 130, 134, 135, 142, 146, 154, 158, 166, 170, 178, 182, 190, 194, 195, 202, 206, 207, 214, 218, 226, 230, 242, 250, 254, 255, 262, 266, 274, 275, 278, 285 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers n such that A324848(n) = 1.

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.

If k is in A324846, then k*prime(k) is in the sequence. - Robert Israel, Mar 22 2019

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

The sequence of terms together with their prime indices begins:

   2: {1}

  10: {1,3}

  14: {1,4}

  15: {2,3}

  22: {1,5}

  26: {1,6}

  34: {1,7}

  38: {1,8}

  45: {2,2,3}

  46: {1,9}

  50: {1,3,3}

  55: {3,5}

  58: {1,10}

  62: {1,11}

  70: {1,3,4}

  74: {1,12}

  82: {1,13}

  86: {1,14}

  94: {1,15}

  98: {1,4,4}

MAPLE

filter:= proc(n) local F;

  F:= select(t -> n mod numtheory:-pi(t[1])=0, ifactors(n)[2]);

  nops(F)=1 and F[1][2]=1

end proc:

select(filter, [$2..1000]); # Robert Israel, Mar 22 2019

MATHEMATICA

Select[Range[100], Total[Cases[If[#==1, {}, FactorInteger[#]], {p_, k_}:>k/; Divisible[#, PrimePi[p]]]]==1&]

CROSSREFS

Cf. A000720, A003963, A112798, A120383, A323440, A324694, A324704, A324846, A324847, A324848, A324849, A324850, A324926, A324929.

Sequence in context: A140510 A277087 A098735 * A345017 A050546 A032384

Adjacent sequences:  A324853 A324854 A324855 * A324857 A324858 A324859

KEYWORD

nonn

AUTHOR

Gus Wiseman, Mar 21 2019

STATUS

approved

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Last modified October 17 17:21 EDT 2021. Contains 348065 sequences. (Running on oeis4.)