A358703 - OEIS

A358703

Sliding numbers: totals, without repetitions, of sums r + s, r >= s, such that 1/r + 1/s = (r + s)/10^k for some k >= 0.

2, 7, 11, 20, 25, 29, 52, 65, 70, 101, 110, 133, 200, 205, 250, 254, 290, 425, 502, 520, 641, 650, 700, 785, 925, 1001, 1010, 1100, 1258, 1330, 2000, 2005, 2050, 2225, 2500, 2504, 2540, 2900, 3157, 3445, 4025, 4250, 5002, 5020, 5200, 6266, 6325, 6410, 6500, 7000

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

See A103182 for more information.

LINKS

Michael De Vlieger, Table of n, a(n) for n = 1..11121 (All terms pertaining to 10^k, k = 0..50)

Michael De Vlieger, Plot of digits of a(n) n = 1..2000, showing nonzero digits in black and 0 in white, 10X exaggeration.

EXAMPLE

We have a(14) = 205 = 80 + 125 = 5 + 200 via 80 * 125 = 10000 and 5 * 200 = 1000. This term appears twice in A103182 for this reason, but only once here. - Michael De Vlieger, Nov 29 2022

MATHEMATICA

nn = 7; f[n_] := Transpose@ {Reverse@ #[[1 ;; Ceiling[Length[#]/2]]], #[[-Ceiling[Length[#]/2] ;; -1]]} &@ Divisors[10^n]; TakeWhile[Union@ Flatten@ Table[Total /@ f[k], {k, 0, nn}], # < Total@ First@ f[nn + 1] &] (* Michael De Vlieger, Nov 29 2022 *)

CROSSREFS

Cf. A103182.

Sequence in context: A141183 A308724 A103182 * A160698 A294114 A144707

Adjacent sequences: A358700 A358701 A358702 * A358704 A358705 A358706

KEYWORD

nonn,base

AUTHOR

Hugo Pfoertner, Nov 28 2022

STATUS

approved