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A045800
0-ish numbers (end in 01, 07, 43, 49).
10
1, 7, 43, 49, 101, 107, 143, 149, 201, 207, 243, 249, 301, 307, 343, 349, 401, 407, 443, 449, 501, 507, 543, 549, 601, 607, 643, 649, 701, 707, 743, 749, 801, 807, 843, 849, 901, 907, 943, 949, 1001, 1007, 1043, 1049, 1101, 1107, 1143, 1149, 1201, 1207
OFFSET
1,2
FORMULA
G.f.: x*(1+6*x+36*x^2+6*x^3+51*x^4)/(1-x-x^4+x^5). - Colin Barker, Jan 23 2012
a(n) = (50*n-8*i^(n*(n+1))-19*(-1)^n-75)/2, where i=sqrt(-1). - Bruno Berselli, Feb 22 2012
MATHEMATICA
LinearRecurrence[{1, 0, 0, 1, -1}, {1, 7, 43, 49, 101}, 60] (* Harvey P. Dale, Jul 26 2015 *)
PROG
(Haskell)
import Data.List (findIndices)
a045800 n = a045800_list !! (n-1)
a045800_list = findIndices (`elem` [1, 7, 43, 49]) $ cycle [0..99]
-- Reinhard Zumkeller, Jan 23 2012
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
More terms from Erich Friedman.
STATUS
approved