A332659 Alternate multiplying and adding prime numbers: a(2n) = a(2n-1) + prime(2n+1) and a(2n-1) = a(2n) * prime(2n-2) for n >= 1.

6, 11, 77, 88, 1144, 1161, 22059, 22082, 640378, 640409, 23695133, 23695174, 1018892482, 1018892529, 54001304037, 54001304096, 3294079549856, 3294079549923, 233879648044533, 233879648044606, 18476492195523874, 18476492195523957, 1644407805401632173

Offset: 1

Author

Adnan Baysal, Feb 18 2020

Keywords

• nonn
• easy

Examples

			a(1) =  2 * 3 =  6;
a(2) =  6 + 5 = 11;
a(3) = 11 * 7 = 77.
		

Crossrefs

Cf. A047904, A047905, A077138, A222559, A332657, A332660.

Programs

Python

from sympy import primerange
p = list(primerange(1, 1000))
def a(n):
    out = p[0] * p[1]
    for i in range(1, n):
        if i % 2:
            out += p[i + 1]
        else:
            out *= p[i + 1]
    return out