The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A320325 Numbers whose product of prime indices is a perfect power. 24
 7, 9, 14, 18, 19, 21, 23, 25, 27, 28, 36, 38, 42, 46, 49, 50, 53, 54, 56, 57, 63, 72, 76, 81, 84, 92, 97, 98, 100, 103, 106, 108, 112, 114, 115, 121, 125, 126, 131, 133, 144, 147, 151, 152, 159, 161, 162, 168, 169, 171, 175, 183, 184, 185, 189, 194, 195, 196 (list; graph; refs; listen; history; text; internal format)
 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. LINKS Table of n, a(n) for n=1..58. EXAMPLE The terms together with their corresponding multiset multisystems (A302242): 7: {{1,1}} 9: {{1},{1}} 14: {{},{1,1}} 18: {{},{1},{1}} 19: {{1,1,1}} 21: {{1},{1,1}} 23: {{2,2}} 25: {{2},{2}} 27: {{1},{1},{1}} 28: {{},{},{1,1}} 36: {{},{},{1},{1}} 38: {{},{1,1,1}} 42: {{},{1},{1,1}} 46: {{},{2,2}} 49: {{1,1},{1,1}} 50: {{},{2},{2}} 53: {{1,1,1,1}} 54: {{},{1},{1},{1}} 56: {{},{},{},{1,1}} 57: {{1},{1,1,1}} 63: {{1},{1},{1,1}} 72: {{},{},{},{1},{1}} 76: {{},{},{1,1,1}} 81: {{1},{1},{1},{1}} MATHEMATICA Select[Range[100], GCD@@FactorInteger[Times@@Cases[FactorInteger[#], {p_, k_}:>PrimePi[p]^k]][[All, 2]]>1&] CROSSREFS Cf. A000720, A001222, A001597, A003963, A056239, A064573, A112798, A302242, A305551, A306017, A319056, A319066, A320322, A320323, A320324. Sequence in context: A145827 A116025 A344011 * A320699 A332514 A353168 Adjacent sequences: A320322 A320323 A320324 * A320326 A320327 A320328 KEYWORD nonn AUTHOR Gus Wiseman, Oct 10 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 2 21:05 EDT 2024. Contains 374875 sequences. (Running on oeis4.)