(LETREC FIRSTSUMS (FIRSTSUMS LAMBDA (K) (FIRST K (SUMS (QUOTE 0) (INTEGERSFROM (QUOTE 1))))) (FIRST LAMBDA (K X) (IF (EQ K (QUOTE 0)) (QUOTE NIL) (CONS (CAR X) (FIRST (SUB K (QUOTE 1)) (FORCE (CDR X)))))) (SUMS LAMBDA (A X) (CONS (ADD A (CAR X)) (DELAY (SUMS (ADD A (CAR X)) (FORCE (CDR X)))))) (INTEGERSFROM LAMBDA (M) (CONS M (DELAY (INTEGERSFROM (ADD M (QUOTE 1))))))) &