A171669 - OEIS

A171669

Pell numbers sandwiched between two numbers having same number of divisors.

12, 5741, 2744210, 15994428, 21300003689580, 723573111879672, 1111984844349868137938112, 293199986221627877463941823267862, 9960168529794442859224531878561050, 27749033099085295754434173207717704165, 66992092050551637663438906713182313772

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OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..19

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. A000005, 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

EXTENSIONS

a(8)-a(11) from Amiram Eldar, Aug 08 2024

STATUS

approved