A222242 In the number n, replace all (decimal) digits '4' with '7' and vice versa.

0, 1, 2, 3, 7, 5, 6, 4, 8, 9, 10, 11, 12, 13, 17, 15, 16, 14, 18, 19, 20, 21, 22, 23, 27, 25, 26, 24, 28, 29, 30, 31, 32, 33, 37, 35, 36, 34, 38, 39, 70, 71, 72, 73, 77, 75, 76, 74, 78, 79, 50, 51, 52, 53, 57, 55, 56, 54, 58, 59, 60, 61, 62, 63, 67, 65, 66, 64, 68, 69, 40, 41, 42, 43, 47, 45

Offset: 0

Author

M. F. Hasler, Feb 13 2013

Keywords

• nonn
• base
• easy

Comments

The map which is applied to primes in A171038.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A222210-A222254; A171013-A171016, A175770, A171018-A171057.

Programs

Mathematica

Table[FromDigits[IntegerDigits[n]/.{4->a,7->b}/.{a->7,b->4}],{n,0,80}] (* Harvey P. Dale, Jul 22 2013 *)

PARI

A222242(n,d=[0, 1, 2, 3, 7, 5, 6, 4, 8, 9])={sum(i=1,#n=digits(n),d[n[i]+1]*10^(#n-i),!n*d[1])} \\ N.B.: digits(0)=[] in PARI (v.2.6)