A115420 Numbers having a 1 in position 4 of their binary expansion.

16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127

Offset: 1

Author

Jeremy Gardiner, Jan 22 2006

Keywords

• base
• easy
• nonn

Comments

One of the mystery calculator sequences: A005408, A042964, A047566, A115419, A115420, A115421.

Examples

			a(1) = 16 = 10000 in binary.
		

Links

• Edd Mann, Mystery Calculator.

Crossrefs

Cf. A005408, A042964, A047566, A115419, A115421.

Programs

Maple

a:= n-> n+15 + 16*iquo(n-1, 16):
seq(a(n), n=1..100);  # Alois P. Heinz, Aug 22 2011

Python

def A115420(n): return ((n-1<<1)&-15|16)+(n-1&15) # Chai Wah Wu, Mar 28 2024