Hofstadter Q sequence: Difference between revisions

=={{header|PL/M}}==

<lang plm>100H:

BDOS: PROCEDURE (FN, ARG); DECLARE FN BYTE, ARG ADDRESS; GO TO 5; END BDOS;

EXIT: PROCEDURE; CALL BDOS(0,0); END EXIT;

PRINT: PROCEDURE (S); DECLARE S ADDRESS; CALL BDOS(9,S); END PRINT;

PRINT$NUMBER: PROCEDURE (N);

DECLARE S (7) BYTE INITIAL ('..... $');

DECLARE (N, P) ADDRESS, C BASED P BYTE;

P = .S(5);

DIGIT:

P = P - 1;

C = N MOD 10 + '0';

N = N / 10;

IF N > 0 THEN GO TO DIGIT;

CALL PRINT(P);

END PRINT$NUMBER;

DECLARE Q (1001) ADDRESS;

DECLARE N ADDRESS;

Q(1)=1;

Q(2)=1;

DO N=3 TO LAST(Q);

Q(N) = Q(N-Q(N-1)) + Q(N-Q(N-2));

END;

CALL PRINT(.'THE FIRST 10 TERMS ARE: $');

DO N=1 TO 10;

CALL PRINT$NUMBER(Q(N));

END;

CALL PRINT(.(13,10,'THE 1000TH TERM IS: $'));

CALL PRINT$NUMBER(Q(1000));

CALL EXIT;

EOF</lang>

{{out}}

<pre>THE FIRST 10 TERMS ARE: 1 1 2 3 3 4 5 5 6 6

THE 1000TH TERM IS: 502</pre>