A045805 5-ish numbers (end in 51, 57, 93, 99).

51, 57, 93, 99, 151, 157, 193, 199, 251, 257, 293, 299, 351, 357, 393, 399, 451, 457, 493, 499, 551, 557, 593, 599, 651, 657, 693, 699, 751, 757, 793, 799, 851, 857, 893, 899, 951, 957, 993, 999, 1051, 1057, 1093, 1099, 1151, 1157, 1193, 1199, 1251, 1257

Offset

1,1

Comments

Any a(n)^(2*k+1), k >= 0, is a member. Also, all products of an odd number of terms or products of a term of this sequence and a term of A045800 are members. Any a(n)^(2*k), k >= 0, as well as products of an even number of terms belong to A045800. - Klaus Purath, Jun 04 2026

Links

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

Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).

Formula

G.f.: x*(51+6*x+36*x^2+6*x^3+x^4)/(1-x-x^4+x^5). - Colin Barker, Jan 23 2012

From Klaus Purath, Jun 04 2026: (Start)

a(n) = a(n-1) + a(n-4) - a(n-5), n >= 6.

a(n) = -A045800(1-n). (End)

Mathematica

Select[Range[50, 1500], MemberQ[{51, 57, 93, 99}, Mod[#, 100]]&] (* Harvey P. Dale, Nov 14 2022 *)

Prog

(Haskell)
import Data.List (findIndices)
a045805 n = a045805_list !! (n-1)
a045805_list = findIndices (`elem` [51, 57, 93, 99]) $ cycle [0..99]
-- Reinhard Zumkeller, Jan 23 2012

Crossrefs

Cf. A045800-A045809.

Cf. A045572, A045797, A045798.

Sequence in context: A060033 A273199 A095525 * A373205 A031410 A308766

Adjacent sequences: A045802 A045803 A045804 * A045806 A045807 A045808

Keyword

nonn,base,easy

Author

J. H. Conway

Extensions

More terms from Erich Friedman

Status

approved