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A053245
Numbers n such that both A053238(n) and A053238(n+1) = 1.
8
20, 49, 56, 79, 108, 132, 145, 170, 177, 230, 253, 277, 289, 307, 347, 382, 405, 412, 424, 437, 495, 548, 585, 592, 633, 645, 704, 734, 752, 764, 789, 802, 841, 854, 930, 943, 967, 974, 1005, 1012, 1053, 1066, 1130, 1154, 1179, 1186, 1216, 1223, 1264
OFFSET
1,1
COMMENTS
Pairs of consecutive 1's occur uncommonly often in A053238.
LINKS
MAPLE
with(numtheory): f := [seq( `if`((sigma(i) > sigma(i+1)), i, print( )), i=1..5000)];
seq(`if`((f[i+2]-f[i+1]=1) and (f[i+1]-f[i]=1), i, print( )), i=1..1500);
PROG
(Haskell)
a053245 n = a053245_list !! (n-1)
a053245_list = f a053242_list where
f (x:x':xs) | x' == x+1 = x : f xs
| otherwise = f (x':xs)
-- Reinhard Zumkeller, Oct 16 2011
KEYWORD
nonn
AUTHOR
Asher Auel, Jan 10 2000
STATUS
approved