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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A324850 Numbers divisible by the product of their prime indices. 41
 1, 2, 4, 6, 8, 12, 16, 24, 28, 30, 32, 36, 48, 56, 60, 64, 72, 96, 112, 120, 128, 144, 152, 156, 168, 180, 192, 216, 224, 240, 256, 288, 304, 312, 330, 336, 360, 384, 432, 448, 476, 480, 512, 576, 608, 624, 660, 672, 720, 768, 784, 828, 840, 848, 864, 888, 896 (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. The multiset of prime indices of n is row n of A112798, with product A003963(n). For example, the prime indices of 30 are {1,2,3}, with product 6, which divides 30, so 30 is in the sequence. LINKS FORMULA n/A003963(n) = A324933(n)/A324934(n). EXAMPLE The sequence of terms together with their prime indices begins:    1: {}    2: {1}    4: {1,1}    6: {1,2}    8: {1,1,1}   12: {1,1,2}   16: {1,1,1,1}   24: {1,1,1,2}   28: {1,1,4}   30: {1,2,3}   32: {1,1,1,1,1}   36: {1,1,2,2}   48: {1,1,1,1,2}   56: {1,1,1,4}   60: {1,1,2,3}   64: {1,1,1,1,1,1}   72: {1,1,1,2,2}   96: {1,1,1,1,1,2} MATHEMATICA Select[Range[100], Divisible[#, Times@@Cases[If[#==1, {}, FactorInteger[#]], {p_, k_}:>PrimePi[p]^k]]&] PROG (PARI) isok(n) = my(f=factor(n)); !(n % prod(k=1, #f~, primepi(f[k, 1])^f[k, 2])); \\ Michel Marcus, Mar 22 2019 CROSSREFS Cf. A003963, A036844, A120383, A324847, A324756, A324758, A324847, A324848, A324849, A324852, A324853, A324856, A324923, A324924, A324925, A324931. Sequence in context: A326504 A058629 A323508 * A095810 A025487 A279537 Adjacent sequences:  A324847 A324848 A324849 * A324851 A324852 A324853 KEYWORD nonn AUTHOR Gus Wiseman, Mar 18 2019 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.

Last modified March 31 03:48 EDT 2020. Contains 333136 sequences. (Running on oeis4.)