A073847 a(0) = 1, c(0) = 1, a(n) for n > 0 is the smallest prime a(n-1) + c(n), where c(n) is composite and larger than c(n-1).

1, 5, 11, 19, 29, 41, 59, 79, 101, 127, 157, 191, 227, 269, 313, 359, 409, 461, 521, 587, 659, 733, 809, 887, 967, 1049, 1151, 1259, 1373, 1489, 1607, 1733, 1861, 1993, 2129, 2267, 2411, 2557, 2707, 2861, 3019, 3181, 3347, 3517, 3691, 3877, 4073, 4271, 4481

Offset

0,2

Comments

Same as A070865 after first term. - David Wasserman, Jun 27 2005

Links

Table of n, a(n) for n=0..48.

Example

a(6) = 59 since 59 = a(5) + c(6) = 41 + 18, 18 is composite and larger than c(5) = 12 and the composite numbers 14, 15, 16 do not lead to a prime when added to 41.

Mathematica

a[n_] := a[n] = NextPrim[a[n - 1] + a[n - 1] - a[n - 2]]; a[0] = 1; a[1] = 5; Table[ a[n], {n, 0, 50}]

Prog

(PARI) {print1(a=1, ", "); c=1; for(n=1, 48, c++; while(isprime(c)||!isprime(a+c), c++); a=a+c; print1(a, ", "))}

Crossrefs

Sequence in context: A110331 A028387 A106071 * A024833 A002327 A078179

Adjacent sequences: A073844 A073845 A073846 * A073848 A073849 A073850

Keyword

nonn

Author

Amarnath Murthy, Aug 14 2002

Extensions

Edited and extended by Klaus Brockhaus and Robert G. Wilson v, Aug 14 2002

Status

approved