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A045801
1-ish numbers (end in 11, 39, 73, 77).
2
11, 39, 73, 77, 111, 139, 173, 177, 211, 239, 273, 277, 311, 339, 373, 377, 411, 439, 473, 477, 511, 539, 573, 577, 611, 639, 673, 677, 711, 739, 773, 777, 811, 839, 873, 877, 911, 939, 973, 977, 1011, 1039, 1073, 1077, 1111, 1139, 1173, 1177, 1211, 1239
OFFSET
1,1
FORMULA
G.f.: x*(11+28*x+34*x^2+4*x^3+23*x^4)/(1-x-x^4+x^5). - Colin Barker, Jan 23 2012
a(n) = (50*n-12*i^(n*(n-1))-9*(-1)^n-25)/2, where i=sqrt(-1). - Bruno Berselli, Feb 23 2012
MATHEMATICA
Table[100n+k, {n, 0, 20}, {k, {11, 39, 73, 77}}]//Flatten (* or *) LinearRecurrence[ {1, 0, 0, 1, -1}, {11, 39, 73, 77, 111}, 80] (* Harvey P. Dale, Jul 05 2019 *)
PROG
(Haskell)
import Data.List (findIndices)
a045801 n = a045801_list !! (n-1)
a045801_list = findIndices (`elem` [11, 39, 73, 77]) $ cycle [0..99]
-- Reinhard Zumkeller, Jan 23 2012
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
More terms from Erich Friedman.
STATUS
approved