A044234 Numbers n such that string 5,7 occurs in the base 8 representation of n but not of n-1.

47, 111, 175, 239, 303, 367, 376, 431, 495, 559, 623, 687, 751, 815, 879, 888, 943, 1007, 1071, 1135, 1199, 1263, 1327, 1391, 1400, 1455, 1519, 1583, 1647, 1711, 1775, 1839, 1903, 1912, 1967, 2031, 2095, 2159, 2223, 2287, 2351

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Links

• Georg Fischer, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A007094.

Programs

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n,8],{5,7}]>0,1,0],{n,2500}],{0,1}][[;;,2]] (* Harvey P. Dale, Jul 10 2024 *)

Formula

a(n) = 512*(n-7)/9 + 376 when n == 7 mod 9; otherwise a(n) = 64*(n - floor((n+1)/9) - 1) + 47. - Bob Selcoe, Apr 01 2016

Extensions

Linear recurrence removed and terms a(54), a(126) etc. corrected by Georg Fischer, Jun 27 2019