A309721 Number of right angles between the segments that are turned "on" when representing n on a 7-segment (calculator) display.

4, 0, 4, 4, 3, 4, 6, 1, 8, 6, 4, 0, 4, 4, 3, 4, 6, 1, 8, 6, 8, 4, 8, 8, 7, 8, 10, 5, 12, 10, 8, 4, 8, 8, 7, 8, 10, 5, 12, 10, 7, 3, 7, 7, 6, 7, 9, 4, 11, 9, 8, 4, 8, 8, 7, 8, 10, 5, 12, 10, 10, 6, 10, 10, 9, 10, 12, 7, 14, 12, 5, 1, 5, 5, 4, 5, 7, 2, 9, 7, 12, 8, 12, 12, 11, 12, 14, 9, 16, 14, 10, 6, 10, 10, 9, 10, 12, 7

Offset: 0

Author

Ivan N. Ianakiev, Aug 14 2019

Keywords

• nonn
• base
• easy

Comments

The display is the one described in A006942 (see also the example section below).

Examples

			To illustrate a(0),...,a(9):
   _     _  _       _   _   _   _   _
  | | |  _| _| |_| |_  |_    | |_| |_|
  |_| | |_  _|   |  _| |_|   | |_|  _|
.
		

Crossrefs

Cf. A006942, A010371, A063720, A277116.

Programs

Mathematica

Evaluate[Table[a[n],{n,0,9}]]={4,0,4,4,3,4,6,1,8,6};
a[n_/;n>9]:=a[Floor[n/10]]+a[Mod[n,10]]; a/@Range[0,100] (* or *)
Table[Total[IntegerDigits[n]/.{0->4,1->0,2->4,3->4,4-> 3,5->4,7->1,9->6}],{n,0,100}]

Formula

a(n) = a(floor(n/10)) + a(n mod 10), for n > 9 (a formula by Reinhard Zumkeller, same for A006942 and A010371).