OFFSET
0,3
LINKS
PROG
(Haskell)
a249873 n = if n == 0 then 0 else 100*a249873 n' + 10*a007953 (2*t) + d
where (n', td) = divMod n 100; (t, d) = divMod td 10
(PARI) a(n) = my(d=Vecrev(digits(n))); forstep (i=2, #d, 2, d[i] = sumdigits(2*d[i])); fromdigits(Vecrev(d)); \\ Michel Marcus, Jan 23 2022
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Nov 08 2014
STATUS
approved