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A267144 Octagonal numbers with prime indices. 1
8, 21, 65, 133, 341, 481, 833, 1045, 1541, 2465, 2821, 4033, 4961, 5461, 6533, 8321, 10325, 11041, 13333, 14981, 15841, 18565, 20501, 23585, 28033, 30401, 31621, 34133, 35425, 38081, 48133, 51221, 56033, 57685, 66305, 68101, 73633, 79381, 83333, 89441, 95765 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..41.

Eric Weisstein's World of Mathematics, Octagonal Number

Eric Weisstein's World of Mathematics, Prime Number

FORMULA

a(n) = prime(n)*(3*prime(n) - 2) = A000040(n)*(3*A000040(n) - 2).

a(n) = A000567(A000040(n)).

a(n) = sigma_0(24^(prime(n) - 1)) = A000005(A009968(A000040(n) - 1)).

MATHEMATICA

Table[Prime[n] (3 Prime[n] - 2), {n, 1, 45}]

PROG

(PARI) lista(nn) = forprime(p=2, nn, print1(p*(3*p-2), ", ")); \\ Altug Alkan, Jan 11 2016

(MAGMA) [NthPrime(n)*(3*NthPrime(n)-2): n in [1..50]]; // Vincenzo Librandi, Jan 12 2016

CROSSREFS

Cf. A000040, A000567, A001248, A034953, A116995, A117961.

Sequence in context: A241522 A096018 A297647 * A240516 A156304 A232049

Adjacent sequences:  A267141 A267142 A267143 * A267145 A267146 A267147

KEYWORD

nonn,easy

AUTHOR

Ilya Gutkovskiy, Jan 11 2016

STATUS

approved

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Last modified February 21 22:56 EST 2018. Contains 299427 sequences. (Running on oeis4.)