SEQUENCE_dat_seq1
The same result is obtained with Serial data type
drop table dat_serial2;
drop SEQUENCE dat_seq1 ;
--
CREATE SEQUENCE dat_seq1;
CREATE TABLE dat_serial2 (
id integer NOT NULL DEFAULT nextval('dat_seq1'),
name varchar(10)
);

INSERT INTO dat_serial2 (name) values('Jacob');
INSERT INTO dat_serial2(name) values('Jashua');
INSERT INTO dat_serial2 (name) values('Swanjee');