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A171669 Pell numbers sandwiched between two numbers having same number of divisors. 0
12, 5741, 2744210, 15994428, 21300003689580, 723573111879672, 1111984844349868137938112 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..7.

MATHEMATICA

f[n_]:=Length[Divisors[n]]; a=1; b=0; c=0; lst={}; Do[c=a+b+c; If[f[c-1]==f[c+1], AppendTo[lst, c]]; a=b; b=c, {n, 80}]; lst

CROSSREFS

Cf. A000129, A005237, A005238, A067889, A171666, A171667, A171668

Sequence in context: A013508 A230749 A003793 * A094268 A208865 A012607

Adjacent sequences:  A171666 A171667 A171668 * A171670 A171671 A171672

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Dec 14 2009

STATUS

approved

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Last modified October 27 02:00 EDT 2021. Contains 348270 sequences. (Running on oeis4.)