OFFSET
1,3
COMMENTS
Whenever a(n) is a multiple of 4, then a(n+1) = a(n) + 1 is also a base 4 perfect digital invariant, with the same exponent k. - M. F. Hasler, Nov 21 2019
LINKS
Joseph Myers, Table of n, a(n) for n=1..6778 (complete to 1500 base 4 digits)
PROG
(PARI) select( {is_A162219(n, b=4)=n<b||forstep(k=logint(n, max(vecmax(b=digits(n, b)), 2)), 2, -1, my(s=vecsum([d^k|d<-b])); s>n||return(s==n))}, [0..10^5]) \\ M. F. Hasler, Nov 21 2019
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Joseph Myers, Jun 28 2009
STATUS
approved