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!)
 A324560 Numbers > 1 where the minimum prime index is less than or equal to the number of prime factors counted with multiplicity. 10
 2, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 26, 27, 28, 30, 32, 33, 34, 36, 38, 39, 40, 42, 44, 45, 46, 48, 50, 51, 52, 54, 56, 57, 58, 60, 62, 63, 64, 66, 68, 69, 70, 72, 74, 75, 76, 78, 80, 81, 82, 84, 86, 87, 88, 90, 92, 93, 94, 96, 98, 99, 100 (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. Also Heinz numbers of a certain type of integer partitions counted by A039900 (but not the type of partitions described in the name). The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k). LINKS FORMULA A055396(a(n)) <= A001222(a(n)). EXAMPLE The sequence of terms together with their prime indices begins:    2: {1}    4: {1,1}    6: {1,2}    8: {1,1,1}    9: {2,2}   10: {1,3}   12: {1,1,2}   14: {1,4}   15: {2,3}   16: {1,1,1,1}   18: {1,2,2}   20: {1,1,3}   21: {2,4}   22: {1,5}   24: {1,1,1,2}   26: {1,6}   27: {2,2,2}   28: {1,1,4}   30: {1,2,3}   32: {1,1,1,1,1} MAPLE with(numtheory): q:= n-> is(pi(min(factorset(n)))<=bigomega(n)): select(q, [\$2..100])[];  # Alois P. Heinz, Mar 07 2019 MATHEMATICA Select[Range[2, 100], PrimePi[FactorInteger[#][[1, 1]]]<=PrimeOmega[#]&] CROSSREFS Cf. A001222, A039900, A055396, A056239, A061395, A106529, A112798. Cf. A324515, A324517, A324519, A324521, A324522, A324560, A324562. Sequence in context: A085492 A338924 A065090 * A227197 A285517 A003254 Adjacent sequences:  A324557 A324558 A324559 * A324561 A324562 A324563 KEYWORD nonn AUTHOR Gus Wiseman, Mar 06 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 September 19 07:06 EDT 2021. Contains 347554 sequences. (Running on oeis4.)