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!)
 A324170 Numbers whose multiset multisystem (A302242) is crossing. 29
 2117, 3973, 4234, 4843, 5183, 5249, 5891, 6351, 6757, 7181, 7801, 7946, 8249, 8468, 8903, 9193, 9686, 9727, 10019, 10063, 10366, 10498, 10585, 11051, 11513, 11567, 11782, 11857, 11919, 12557, 12629, 12702, 12851, 13021, 13193, 13459, 13514, 13631, 14123, 14362 (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. The multiset multisystem of n is obtained by taking the multiset of prime indices of each prime index of n. A multiset of multisets is crossing if it contains a 2-element submultiset of the form {{...x...y...}, {...z...t...}} where x < z < y < t or z < x < t < y. LINKS EXAMPLE The sequence of terms together with their multiset multisystems begins:   2117: {{1,3},{2,4}}   3973: {{1,3},{2,5}}   4234: {{},{1,3},{2,4}}   4843: {{1,3},{2,6}}   5183: {{1,1,3},{2,4}}   5249: {{1,3},{1,2,4}}   5891: {{1,4},{2,5}}   6351: {{1},{1,3},{2,4}}   6757: {{1,3},{2,7}}   7181: {{1,4},{2,6}}   7801: {{1,3},{2,8}}   7946: {{},{1,3},{2,5}}   8249: {{2,4},{1,2,3}}   8468: {{},{},{1,3},{2,4}}   8903: {{1,3},{2,2,4}}   9193: {{1,3},{1,2,5}}   9686: {{},{1,3},{2,6}}   9727: {{1,1,3},{2,5}} MATHEMATICA primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]]; croXQ[stn_]:=MatchQ[stn, {___, {___, x_, ___, y_, ___}, ___, {___, z_, ___, t_, ___}, ___}/; x

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 28 13:24 EDT 2020. Contains 337393 sequences. (Running on oeis4.)