OFFSET
0,2
COMMENTS
Number of endpoints: 0,8 - zero, 6,9 - one, 1,2,3,5,7 - two, 4 - four. - Michael B. Porter, Oct 28 2017
FORMULA
a(10*n + d) = a(n) + e where e is the number of endpoints of single digit d. - David A. Corneth, Oct 28 2017
EXAMPLE
The digit 1 has two endpoints, and the digit 8 has no endpoints, so a(18) = 2. - Michael B. Porter, Oct 28 2017
PROG
(PARI) a(n)=vecsum(apply(d->[0, 2, 2, 2, 4, 2, 1, 2, 0, 1][d+1], digits(n))); \\ based on program for A027386 by Andrew Howroyd, Michael B. Porter, Oct 26 2017
CROSSREFS
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
a(6) corrected by Michael B. Porter, Oct 28 2017 (per Andrew Howroyd)
a(27) to a(80) by Michael B. Porter, Oct 28 2017
STATUS
approved