A050709 Composites c that reach a prime after 5 iterations of c-> c+sum of prime factors of c.

49, 50, 52, 56, 84, 88, 169, 176, 180, 198, 220, 302, 322, 336, 339, 363, 364, 372, 387, 402, 406, 407, 424, 429, 434, 442, 492, 494, 508, 552, 553, 562, 589, 612, 628, 633, 650, 708, 724, 744, 760, 788, 816, 819, 843, 848, 860, 861, 862, 870, 872, 896, 918

Offset

1,1

Links

Table of n, a(n) for n=1..53.

Example

49 is a term:
Iteration 1: 49 = 7*7 so 49 + (7+7) = 49 + 14 = 63 and composite.
Iteration 2: 63 = 3*3*7 so 63 + (3+3+7) = 63 + 13 = 76 and composite.
Iteration 3: 76 = 2*2*19 so 76 + (2+2+19) = 76 + 23 = 99 and composite.
Iteration 4: 99 = 3*3*11 so 99 + (3+3+11) = 99 + 17 = 116 and composite.
Iteration 5: 116 = 2*2*29 so 116 + (2+2+29) = 116 + 33 = 149 and prime.

Crossrefs

Cf. A050703, A050704, A050705, A050706, A050707, A050708, A050710.

Sequence in context: A198435 A165870 A266803 * A371969 A037412 A176309

Adjacent sequences: A050706 A050707 A050708 * A050710 A050711 A050712

Keyword

nonn

Author

Patrick De Geest, Aug 15 1999

Extensions

Name edited by Michel Marcus, Oct 18 2019

Status

approved