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 A308101 Numbers that set records for longest chains of "chained prime factors" of A308099. 2
 46, 1426, 120842, 12205042, 1257119326, 219043888774, 37904185920914, 8346405168610942, 1610856197541911806, 494532852645366924442, 159830762776306031303126, 63895498657264777378395106, 25160765901619915831898554178, 9890836489141547229675646151234 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Length m Distinct prime factors ------ ---------- ---------------------- 2 46 {2,23} 3 1426 {2,23,31} 4 120842 {2,23,37,71} 5 12205042 {2,23,37,71,101} 6 1257119326 {2,23,37,71,101,103} 7 219043888774 {2,23,37,71,101,131,137} 8 37904185920914 {2,23,37,71,101,131,151,157} 9 8346405168610942 {2,23,37,71,101,131,151,181,191} LINKS Table of n, a(n) for n=1..14. MATHEMATICA ric[pr_, lp_, tg_] := Block[{cp}, If[tg==0, If[pr < curr, curr=pr], cp = NextPrime@ lp; While[pr cp^tg < curr, If[First@ IntegerDigits@ cp == Mod[lp, 10], ric[pr cp, cp, tg-1]]; cp = NextPrime@ cp]]]; a[n_] := Block[ {q = 2}, curr = Infinity; While[q^(n + 1) < curr, ric[q, q, n]; q = NextPrime@ q]; curr]; Array[a, 14] (* Giovanni Resta, Jun 25 2019 *) CROSSREFS Cf. A308099, A308252. Sequence in context: A103725 A332858 A264505 * A291129 A115608 A318044 Adjacent sequences: A308098 A308099 A308100 * A308102 A308103 A308104 KEYWORD nonn,base AUTHOR Giorgos Kalogeropoulos, May 12 2019 EXTENSIONS a(6)-a(14) from Giovanni Resta, Jun 25 2019 STATUS approved

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Last modified July 12 17:07 EDT 2024. Contains 374251 sequences. (Running on oeis4.)