A346297 Slowest growing sequence of semiprimes such that any accumulating sum is a semiprime.

4, 6, 15, 21, 39, 49, 51, 62, 74, 77, 87, 94, 95, 111, 129, 133, 142, 158, 166, 178, 183, 185, 187, 203, 205, 209, 214, 218, 226, 237, 287, 298, 302, 309, 323, 326, 334, 346, 355, 361, 362, 365, 371, 382, 394, 398, 451, 473, 478, 489, 497, 519, 529, 554, 562, 591, 597, 623, 649, 662, 669, 679, 689, 697, 707, 717, 746

Offset: 1

Author

Zak Seidov, Sep 28 2021

Keywords

• nonn

Examples

			4 + 6 = 10 = 2*5, 10 + 15 = 25 = 5*5, 25 + 21 = 46 = 2*23.
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001222, A001358, A116656.

Programs

Mathematica

s = {4}; t = 4; Do[While[2 != PrimeOmega[n] || 2 != PrimeOmega[t + n] , n++]; AppendTo[s, n]; t = t + n; n++, {50}]; s

PARI

issemi(n)=bigomega(n)==2;
first(n)=my(v=vector(n),s,t); s=v[1]=4; for(k=2,n, t=v[k-1]; while(!issemi(t++) || !issemi(s+t), ); s+=v[k]=t); v; \\ Charles R Greathouse IV, Oct 02 2021