OFFSET
0,4
COMMENTS
The integers are displayed as in A063720, where the negative integers are depicted by using 1 segment more for the minus sign.
LINKS
FORMULA
EXAMPLE
a(7) = 20 since -111, -77, -41, -14, 8, 12, 13, 15, 16, 19, 21, 31, 47, 51, 61, 74, 91, 117, 171 and 711 are displayed by 7 segments.
__ __ __
__ | | | __ | | __ |__| | __ | |__| |__|
| | | | | | | | | |__|
(-111) (-77) (-41) (-14) (8)
__ __ __ __ __
| __| | __| | |__ | |__ | |__| __| |
| |__ | __| | __| | |__| | | |__ |
(12) (13) (15) (16) (19) (21)
__ __ __ __
__| | |__| | |__ | |__ | | |__|
__| | | | __| | |__| | | |
(31) (47) (51) (61) (74)
__ __ __ __
|__| | | | | | | | | | |
| | | | | | | | | | |
(91) (117) (171) (711)
MATHEMATICA
P[x_]:=x^2+x^3+x^4+5x^5+x^6+x^7; c[n_]:=Coefficient[Sum[P[x]^k, {k, Max[1, Ceiling[n/7]], Floor[n/2]}], x, n]; b[n_]:=c[n]-c[n-6]; (* A343314 *)
a[n_]:=If[n!=7, b[n]+b[n-1], 20]; Array[a, 39, 0]
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Stefano Spezia, Dec 31 2021
STATUS
approved