OFFSET
1,2
COMMENTS
The sum of two successive terms is odd and the sum of two successive digits is odd, too. The sequence could be started with an additional 0 and then be extended always with the smallest integer not yet present in the sequence and not leading to a contradiction. - Eric Angelini and Jean-Marc Falcoz, Jan 31 2017
LINKS
Carole Dubois, Table of n, a(n) for n = 1..15484
Eric Angelini, Odd/even: integers and digits alternate, SeqFan mailing list, Oct 06 2012
FORMULA
Conjectures from Colin Barker, Jan 16 2020: (Start)
G.f.: x*(1 + x + x^2 + x^3 + x^4 + x^5 + x^6 + x^7 + x^8 + 201*x^9 - 110*x^10 + 110*x^11 - 110*x^12 + 110*x^13 - 110*x^14 + 110*x^15 - 110*x^16 + 110*x^17 - 110*x^18 - 80*x^19) / ((1 - x)^2*(1 + x)*(1 - x + x^2 - x^3 + x^4)*(1 + x + x^2 + x^3 + x^4)).
a(n) = a(n-1) + a(n-10) - a(n-11) for n>20.
(End)
PROG
(PARI) {a(n, show=1, a=1, u)=for( i=2, n, u+=1<<a; show & print1(a", "); for(t=1, 9e9, bittest(u, t) & next; bittest(t+a, 0) || next; !bittest(a%10 + t\10^(#Str(t)-1), 0) & (t+=10^(#Str(t)-1)-1) & next; my(tt=t); while( tt>9, bittest( tt+0+tt\=10, 0 ) || next(2)); a=t; break )); a}
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Eric Angelini and M. F. Hasler, Oct 06 2012
STATUS
approved