A193570 Unhappy numbers which enter the cycle (4, 16, 37, 58, 89, 145, 42, 20) at 145.

77, 98, 145, 149, 194, 238, 283, 289, 298, 328, 358, 382, 385, 419, 456, 465, 491, 538, 546, 564, 583, 645, 654, 678, 687, 707, 768, 770, 786, 789, 798, 809, 823, 829, 832, 835, 853, 867, 876, 879, 890, 892, 897, 908, 914, 928, 941, 978, 980, 982, 987

Offset: 1

Author

Martin Renner, Jul 31 2011

Keywords

• nonn
• base

Examples

			25889 is such a number of height 4 because it enters the cycle at 145 in 4 steps: 25889 -> 238 -> 77 -> 98 -> 145 -> 42 -> 20 -> 4 -> 16 -> 37 -> 58 -> 89 -> 145 -> ...
		

Links

• Eric Weisstein's World of Mathematics, Unhappy Number.

Crossrefs

Cf. A031177, A039943.

Programs

Maple

S:=proc(n) local Q,k,N,z; Q:=[n]; for k from 1 do N:=convert(Q[k],base,10); z:=sum(N['i']^2,'i'=1..nops(N)); if not member(z,Q) then Q:=[op(Q),z]; else Q:=[op(Q),z]; break; fi; od; return Q; end:
a:=[]: for i from 1 while nops(a)<30 do Q:=S(i); A:=Q[nops(Q)]; if A=145 then a:=[op(a),i] fi; od: print(op(a));