A088999 Flip 6,9 numbers: if number k contains decimal digit '6' or '9', then flip all occurrences of '6' to '9' and vice versa.

9, 6, 19, 16, 29, 26, 39, 36, 49, 46, 59, 56, 90, 91, 92, 93, 94, 95, 99, 97, 98, 96, 79, 76, 89, 86, 60, 61, 62, 63, 64, 65, 69, 67, 68, 66, 109, 106, 119, 116, 129, 126, 139, 136, 149, 146, 159, 156, 190, 191, 192, 193, 194, 195, 199, 197, 198, 196, 179, 176, 189

Offset

1,1

Comments

For digits d of n if d = 6 make it 9 else if d = 9 make it 6.

However, numbers containing neither digit 6 nor 9 are not terms (cf. A222251).

Links

Table of n, a(n) for n=1..61.

Prog

(PARI) flip69(n) = { for(x=1, n, y=x; v=0; f=0; ln =length(Str(x)); a = vector(ln); forstep(j=ln, 1, -1, r = y%10; a[j]=r; if(r==6, a[j] = 9; f=1); if(r==9, a[j] = 6; f=1); y = floor(y/10); ); forstep(j=ln, 1, -1, v=v+a[j]*10^(ln-j) ); if(f, print1(v", ")); ) }
(Python)
def has69(s): return '6' in s or '9' in s
def flp69(s): return s.replace("6", "-").replace("9", "6").replace("-", "9")
def aupto(lim):
    return [int(flp69(s)) for s in map(str, range(lim+1)) if has69(s)]
print(aupto(186)) # Michael S. Branicky, Sep 06 2021

Crossrefs

Cf. A171055, A222251.

Sequence in context: A102648 A272960 A040074 * A073782 A156033 A196005

Adjacent sequences: A088996 A088997 A088998 * A089000 A089001 A089002

Keyword

nonn,base

Author

Cino Hilliard, Nov 02 2003

Status

approved