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A077065 Semiprimes of form prime - 1. 5
4, 6, 10, 22, 46, 58, 82, 106, 166, 178, 226, 262, 346, 358, 382, 466, 478, 502, 562, 586, 718, 838, 862, 886, 982, 1018, 1186, 1282, 1306, 1318, 1366, 1438, 1486, 1522, 1618, 1822, 1906, 2026, 2038, 2062, 2098, 2206, 2446, 2458, 2578, 2818, 2878, 2902 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

a(n) = A005385(n)-1 = 2*A005384(n).

There are 670 semiprimes of form prime-1 below 100,000.

EXAMPLE

A001358(16)=46=2*23 is a term as 46=A000040(15)-1=47-1.

MATHEMATICA

Select[Range[6000], Plus@@Last/@FactorInteger[#]==2&&PrimeQ[#+1]&] (* From Vladimir Joseph Stephan Orlovsky, May 08 2011 *)

CROSSREFS

Cf. A006093, A001358, A000040, A077068.

Sequence in context: A076995 A096817 A185913 * A131867 A032392 A136838

Adjacent sequences:  A077062 A077063 A077064 * A077066 A077067 A077068

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 23 2002

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Last modified February 17 20:50 EST 2012. Contains 206085 sequences.