A076975 - OEIS

A076975

a(1) = 1, a(2n) = smallest composite number > (2n-1)-th partial sum of the sequence itself and a(2n+1) = smallest prime > 2n-th partial sum of the sequence.

1, 4, 7, 14, 29, 56, 113, 225, 457, 908, 1823, 3638, 7283, 14559, 29123, 58241, 116483, 232965, 465931, 931861, 1863731, 3727453, 7454933, 14909839, 29819701, 59639379, 119278801, 238557559, 477115271, 954230389, 1908460819, 3816921597

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

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..32.

PROG

(PARI) print1(1, ", "); s=1; for(i=2, 100, n=s+1; if(i%2==0, while( isprime(n), n++), while(!isprime(n), n++)); s+=n; print1(n, ", ")) - Lambert Herrgesell (zero815(AT)googlemail.com), Mar 09 2006

CROSSREFS

Cf. A076974.

Sequence in context: A305124 A094968 A049946 * A050343 A245002 A199628

Adjacent sequences: A076972 A076973 A076974 * A076976 A076977 A076978

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Oct 23 2002

EXTENSIONS

More terms from Lambert Herrgesell (zero815(AT)googlemail.com), Mar 09 2006

STATUS

approved