A182081 Next semiprime after the partial sum of the first n semiprimes.

6, 14, 21, 33, 46, 62, 82, 106, 129, 155, 187, 221, 259, 295, 334, 381, 427, 478, 533, 591, 649, 713, 778, 849, 921, 995, 1077, 1165, 1253, 1337, 1437, 1522, 1618, 1711, 1814, 1927, 2041, 2159, 2279, 2402, 2533, 2643, 2773, 2906, 3039, 3183, 3326, 3466, 3611

Offset

1,1

Comments

This is to A202301 next prime after the partial sum of the first n primes as A001358 semiprimes is to A000040 primes.

Links

Alois P. Heinz, Table of n, a(n) for n = 1..1000

Formula

a(n) = min { k > A062198(n) and k in A001358 }.

Example

a(10) = 155 because 4 + 6 + 9 + 10 + 14 + 15 + 21 + 22 + 25 + 26 = 152, and the next semiprime after 152 is 155.

Maple

h:= proc(m) local k;
      for k from m+1 while isprime(k) or
        add (i[2], i=ifactors(k)[2])<>2 do od; k
    end:
b:= proc(n)
      b(n):= h(b(n-1))
    end: b(0):=0:
s:= proc(n)
      s(n):= b(n) +s(n-1)
    end: s(0):=0:
a:= n-> h(s(n)):
seq (a(n), n=1..60); # Alois P. Heinz, Apr 10 2012

Crossrefs

Cf. A001358, A062198, A202301.

Sequence in context: A110223 A190504 A175582 * A125086 A195063 A138290

Adjacent sequences: A182078 A182079 A182080 * A182082 A182083 A182084

Keyword

nonn,easy

Author

Jonathan Vos Post, Apr 10 2012

Extensions

More terms from Alois P. Heinz, Apr 10 2012

Status

approved