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A129512
Numbers with at least two pairs of distinct divisors having equal differences.
4
6, 12, 15, 18, 20, 24, 28, 30, 36, 40, 42, 45, 48, 54, 56, 60, 63, 66, 70, 72, 75, 78, 80, 84, 88, 90, 91, 96, 99, 100, 102, 105, 108, 110, 112, 114, 120, 126, 130, 132, 135, 138, 140, 144, 150, 153, 156, 160, 162, 165, 168, 174, 176, 180, 182, 186, 189, 190, 192, 195
OFFSET
1,1
COMMENTS
A129510(a(n)) < A066446(a(n)).
LINKS
EXAMPLE
See example for a(12)=45 in A129510.
PROG
(Haskell)
import Data.List.Ordered (minus)
a129512 n = a129512_list !! (n-1)
a129512_list = minus [1..] a129511_list
-- Reinhard Zumkeller, Aug 10 2015
(PARI) is(n)=my(d=divisors(n)); for(i=1, #d-2, for(j=i+1, #d-1, for(k=1, #d, if(i!=k && setsearch(d, d[j]-d[i]+d[k]), return(1))))); 0 \\ Charles R Greathouse IV, Aug 26 2015
CROSSREFS
Cf. A129510, A066446, A129511 (complement).
Subsequences: A008588, A008597, A129521, A259366.
Sequence in context: A005279 A343281 A375611 * A259366 A196391 A343207
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Apr 19 2007
STATUS
approved