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 A181093 p*(p+2)/3 where p and p+4 are primes. 0
 5, 21, 65, 133, 481, 645, 1541, 2133, 3201, 3605, 4033, 5461, 8965, 12545, 16725, 17633, 25761, 31621, 32865, 40833, 48133, 52801, 64533, 69921, 71765, 79381, 83333, 125665, 138245, 151425, 182533, 191521, 197633, 226325, 243105, 246533, 256961, 260485, 274821 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For p>3, p == 1 mod 6 and p(p+2) == 0 mod 3, hence, except for the first term, a(n) = subsequence of A014641 Odd octagonal numbers: (2n+1)(6n+1). LINKS EXAMPLE p=3,p+4=7 are primes and a(1)=3*5/3=3, p=7,p+4=11 are primes and a(2)=7*9/3=21=A014641(2), p=13,p+4=17 are primes and a(3)=13*15/3=65=A014641(3). MATHEMATICA # (# + 2)/3 & /@ Select[Prime@Range@140, PrimeQ[# + 4] &] PROG (PARI) {forprime (p=3, 10^3, isprime(p+4)&print1(p*(p+2)/3, ", "))} CROSSREFS Cf. A014641. Sequence in context: A342379 A146822 A146223 * A055384 A271540 A272987 Adjacent sequences:  A181090 A181091 A181092 * A181094 A181095 A181096 KEYWORD nonn AUTHOR Zak Seidov, Jan 23 2011 EXTENSIONS More terms from Michel Marcus, Mar 04 2014 STATUS approved

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Last modified June 22 21:29 EDT 2021. Contains 345393 sequences. (Running on oeis4.)