Van Eck sequence: Difference between revisions

=={{header|COBOL}}==

<lang cobol> IDENTIFICATION DIVISION.

PROGRAM-ID. VAN-ECK.

DATA DIVISION.

WORKING-STORAGE SECTION.

01 CALCULATION.

02 ECK PIC 999 OCCURS 1000 TIMES.

02 I PIC 9999.

02 J PIC 9999.

01 OUTPUT-FORMAT.

02 ITEM PIC ZZ9.

02 IDX PIC ZZZ9.

PROCEDURE DIVISION.

B. PERFORM GENERATE-ECK.

PERFORM SHOW VARYING I FROM 1 BY 1 UNTIL I = 11.

PERFORM SHOW VARYING I FROM 991 BY 1 UNTIL I = 1001.

STOP RUN.

SHOW.

MOVE I TO IDX.

MOVE ECK(I) TO ITEM.

DISPLAY 'ECK(' IDX ') = ' ITEM.

GENERATE-ECK SECTION.

B. SET ECK(1) TO 0.

SET I TO 1.

PERFORM GENERATE-TERM

VARYING I FROM 2 BY 1 UNTIL I = 1001.

GENERATE-TERM SECTION.

B. SUBTRACT 2 FROM I GIVING J.

LOOP.

IF J IS LESS THAN 1 GO TO TERM-IS-NEW.

IF ECK(J) = ECK(I - 1) GO TO TERM-IS-OLD.

SUBTRACT 1 FROM J.

GO TO LOOP.

TERM-IS-NEW.

SET ECK(I) TO 0.

GO TO DONE.

TERM-IS-OLD.

COMPUTE ECK(I) = (I - J) - 1.

DONE. EXIT.</lang>

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<pre>ECK( 1) = 0

ECK( 2) = 0

ECK( 3) = 1

ECK( 4) = 0

ECK( 5) = 2

ECK( 6) = 0

ECK( 7) = 2

ECK( 8) = 2

ECK( 9) = 1

ECK( 10) = 6

ECK( 991) = 4

ECK( 992) = 7

ECK( 993) = 30

ECK( 994) = 25

ECK( 995) = 67

ECK( 996) = 225

ECK( 997) = 488

ECK( 998) = 0

ECK( 999) = 10

ECK(1000) = 136</pre>