A342730 a(n) = floor((frac(e*n) + 1) * prime(n+1)).

2, 5, 7, 8, 20, 20, 22, 19, 40, 42, 36, 70, 66, 57, 49, 94, 88, 73, 129, 116, 99, 85, 149, 135, 120, 197, 172, 149, 121, 206, 196, 165, 271, 236, 211, 172, 291, 256, 216, 175, 309, 262, 223, 364, 316, 263, 219, 392, 335, 273, 445, 390, 325, 268, 459, 395

Offset: 0

Author

Simon Strandgaard, Mar 19 2021

Keywords

• nonn
• look

Examples

			x(n) = frac(e * n) + 1,
a(0) = floor(x(0) * prime(1)) = floor(1.00 *  2) =  2,
a(1) = floor(x(1) * prime(2)) = floor(1.72 *  3) =  5,
a(2) = floor(x(2) * prime(3)) = floor(1.44 *  5) =  7,
a(3) = floor(x(3) * prime(4)) = floor(1.15 *  7) =  8,
a(4) = floor(x(4) * prime(5)) = floor(1.87 * 11) = 20.
		

Links

• Simon Strandgaard, Plot of 400 terms

Crossrefs

Cf. A000040, A001113.

Programs

Mathematica

Array[Floor[(Mod[E #, 1] + 1) Prime[# + 1]] &, 56, 0] (* Michael De Vlieger, Mar 19 2021 *)

PARI

a(n) = floor((frac(exp(1)*n) + 1) * prime(n+1)); \\ Michel Marcus, Mar 20 2021

Ruby

require 'prime'
values = []
primes = Prime.first(20)
primes.each_with_index do |prime, n|
    x = ((n * Math::E) % 1) + 1
    values << (x * prime).floor
end
p values