A222714 Smallest i such that prime(n) divides gcd(sigma(i), phi(i)) (cf. A009223).

3, 14, 88, 116, 989, 477, 6901, 7067, 6439, 10207, 4976, 10877, 13529, 44461, 79523, 22577, 250277, 62023, 107869, 161027, 75008, 49769, 55277, 183296, 75077, 612463, 381923, 412163, 712423, 153679, 32576, 137549, 450181, 154289, 1776377, 1642577, 491723, 637981, 3903791, 239777, 642251, 1572889, 1608983, 1192739, 2791489, 316409, 888731, 4773091, 4942243, 1256293

Offset

1,1

Links

Table of n, a(n) for n=1..50.

Example

Given A009223 = 1, 1, 2, 1, 2, 2, 2, 1, 1, 2, 2, 4, 2, 6, 8, 1, 2, 3, ...
prime(1)=2 first divides A009223(3); prime(2)=3 first divides A009223(14)=6; prime(3)=5 first divides both sigma(88)=180 and phi(88)=40, so A222714(3)=88.

Prog

(PARI) A009223_hunt(x)=local(n=0, g); while(n++, g=A009223(n); if(g%x, , return(n)));
for(x=1, 50, print1(A009223_hunt(prime(x))", "))

Crossrefs

Cf. A009223. Subsequence of A222713.

Sequence in context: A332256 A335849 A185323 * A199548 A355294 A038170

Adjacent sequences: A222711 A222712 A222713 * A222715 A222716 A222717

Keyword

nonn

Author

Phil Carmody, Mar 01 2013

Status

approved