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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 December 1 11:35 EST 2021. Contains 349429 sequences. (Running on oeis4.)