A309672 Composite terms of A007755.

2329, 4369, 10537, 35209, 281929, 1114129, 8978569, 16843009, 143163649, 286331153, 1086374209, 4295098369, 9198250129, 18325194049, 36507844609, 73016672273, 139055899009, 277033877569, 586397253889, 1103840280833, 4673067091009, 9382516064513, 17868687216769

Offset: 1

Author

Jeppe Stig Nielsen, Oct 05 2019

Keywords

• nonn

Comments

10537 is a term because it is composite (= 41*257) and the totient (A000010) iterating "trajectory" starting from 10537 and ending in 1 is longer (length 15) than any similar trajectory starting from a (prime or nonprime) N < 10537.

Crossrefs

Cf. A000010, A003434, A049108, A007755, A098196.