A193570 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..51.

Eric Weisstein's World of Mathematics, Unhappy Number.

EXAMPLE

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 -> ...

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));

CROSSREFS

Cf. A031177, A039943.

Sequence in context: A064902 A247682 A127335 * A154534 A235867 A274967

Adjacent sequences: A193567 A193568 A193569 * A193571 A193572 A193573

KEYWORD

nonn,base

AUTHOR

Martin Renner, Jul 31 2011

STATUS

approved