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A169834 Numbers n such that d(n-1) = d(n) = d(n+1). 6
34, 86, 94, 142, 202, 214, 218, 231, 243, 244, 302, 375, 394, 446, 604, 634, 664, 698, 903, 922, 1042, 1106, 1138, 1262, 1275, 1310, 1335, 1346, 1402, 1642, 1762, 1833, 1838, 1886, 1894, 1925, 1942, 1982, 2014, 2055, 2102, 2134, 2182, 2218, 2265, 2306, 2344, 2362 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Erich Friedman, What's Special About This Number? (See entry 34.)

MATHEMATICA

d[n_] := DivisorSigma[0, n];

samedQ[n_] := d[n-1] == d[n] == d[n+1];

Select[Range[3000], samedQ] (* Jean-Fran├žois Alcover, Aug 01 2018 *)

PROG

(Haskell)

a169834 n = a169834_list !! (n-1)

a169834_list = f a051950_list [0..] where

   f (0:0:ws) (x:y:zs) = y : f (0:ws) (y:zs)

   f (_:v:ws) (_:y:zs) = f (v:ws) (y:zs)

-- Reinhard Zumkeller, Aug 31 2014

CROSSREFS

Cf. A000005, A005238.

Cf. A051950.

Sequence in context: A278311 A213025 A086005 * A248201 A140602 A067977

Adjacent sequences:  A169831 A169832 A169833 * A169835 A169836 A169837

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jun 02 2010

STATUS

approved

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Last modified December 15 22:53 EST 2018. Contains 318157 sequences. (Running on oeis4.)