VOOZH about

URL: https://oeis.org/A377185

⇱ A377185 - OEIS

login
A377185
Average of twin prime pairs A014574 such that the largest odd divisor of the average is the midpoint of the cousin prime pairs A087679.
1
18, 30, 42, 60, 72, 138, 180, 198, 240, 312, 420, 462, 618, 660, 882, 1032, 1152, 1230, 1290, 1320, 1482, 1722, 1878, 2592, 2688, 2970, 3120, 3168, 3300, 3330, 3360, 3390, 3528, 3540, 3672, 4002, 4128, 4482, 5280, 5418, 5502, 6660, 6690, 6780, 7350, 7590, 7758, 8010, 8088, 8820, 9042
OFFSET
1,1
LINKS
EXAMPLE
18 is in this sequence because:
(a) 18 is average of twin prime pair {17, 19};
(b) the largest odd divisor of 18 is 9;
(c) 9 is the midpoint of the cousin prime pair {7, 11}.
MATHEMATICA
lod[m_]:=Select[Divisors[m+1], OddQ][[-1]]; Select[Prime[Range[1130]], PrimeQ[#+2]&&PrimeQ[lod[#]-2]&&PrimeQ[lod[#]+2]&]+1 (* James C. McMahon, Nov 17 2024 *)
PROG
(Magma) [n: n in [4..10^4] | IsPrime(n-1) and IsPrime(n+1) and IsPrime((n div 2^Valuation(n, 2))-2) and IsPrime((n div 2^Valuation(n, 2))+2)];
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved