Numbers k such that k + sigma(k) + phi(k) is a triangular number.

Terms

a(0) =1a(1) =2a(2) =5a(3) =7a(4) =9a(5) =16a(6) =144a(7) =186a(8) =410a(9) =656a(10) =680a(11) =805a(12) =963a(13) =968a(14) =1152a(15) =1331a(16) =1419a(17) =1476a(18) =1557a(19) =1608a(20) =2158a(21) =2220a(22) =2376a(23) =2401a(24) =2529a(25) =2840a(26) =3376a(27) =3447a(28) =3570a(29) =3591