A073792 Replace 5^k with (-5)^k in base 5 expansion of n.

0, 1, 2, 3, 4, -5, -4, -3, -2, -1, -10, -9, -8, -7, -6, -15, -14, -13, -12, -11, -20, -19, -18, -17, -16, 25, 26, 27, 28, 29, 20, 21, 22, 23, 24, 15, 16, 17, 18, 19, 10, 11, 12, 13, 14, 5, 6, 7, 8, 9, 50, 51, 52, 53, 54, 45, 46, 47, 48, 49, 40, 41, 42, 43, 44, 35, 36, 37, 38, 39, 30, 31, 32, 33, 34

Offset: 0

Author

Robert G. Wilson v, Aug 12 2002

Keywords

• base
• easy
• sign

Comments

Base 5 representation for n converted from base -5 to base 10.

Links

• Dana G. Korssjoen, Biyao Li, Stefan Steinerberger, Raghavendra Tripathi, and Ruimin Zhang, Finding structure in sequences of real numbers via graph theory: a problem list, arXiv:2012.04625 [math.CO], 2020-2021.

Crossrefs

Cf. A007091, A073786, A053985, A065369, A073791, A073793, A073794, A073795, A073796 & A073835.

Programs

Mathematica

f[n_Integer, b_Integer] := Block[{l = IntegerDigits[n]}, Sum[l[[ -i]]*(-b)^(i - 1), {i, 1, Length[l]}]]; a = Table[ FromDigits[ IntegerDigits[n, 5]], {n, 0, 80}]; b = {}; Do[b = Append[b, f[a[[n]], 5]], {n, 1, 80}]; b

Formula

a(5*k+m) = -5*a(k)+m for 0 <= m < 5. - Chai Wah Wu, Jan 16 2020