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A108607 4-almost primes whose sum of factors is a prime. 5
40, 54, 56, 88, 90, 104, 136, 184, 198, 210, 248, 250, 294, 296, 328, 350, 376, 390, 414, 424, 462, 488, 522, 536, 550, 570, 584, 664, 686, 714, 776, 798, 808, 824, 850, 856, 858, 930, 950, 954, 1014, 1048, 1062, 1110, 1190, 1208, 1210, 1218, 1256, 1274, 1278 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

40=2*2*2*5 (4-almost prime) and 2+2+2+5=11 is a prime.

PROG

(PARI) is(n)=my(f=factor(n)); sum(i=1, #f~, f[i, 2])==4 && isprime(sum(i=1, #f~, f[i, 1]*f[i, 2])) \\ Charles R Greathouse IV, Oct 11 2013

CROSSREFS

Cf. A107707, A108608, A108609 (resp.) 3, 5, 6 (resp.)-almost primes whose sum of factors is a prime.

Sequence in context: A255392 A116299 A110227 * A109730 A100333 A260609

Adjacent sequences:  A108604 A108605 A108606 * A108608 A108609 A108610

KEYWORD

nonn

AUTHOR

Zak Seidov, Jun 12 2005

STATUS

approved

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Last modified October 23 16:46 EDT 2019. Contains 328373 sequences. (Running on oeis4.)