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A247233
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Smallest m such that A075323(m) = n-th odd prime, or zero, if no such m exists.
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2
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1, 2, 3, 4, 5, 11, 6, 7, 12, 8, 9, 29, 15, 10, 13, 16, 17, 14, 30, 23, 18, 19, 509, 24, 25, 20, 55, 21, 37, 26, 22, 35, 27, 31, 38, 33, 56, 28, 36, 43, 32, 34, 39, 41, 51, 45, 44, 53, 47, 40, 42, 65, 52, 46, 49, 67, 161, 48, 54, 63, 59, 66, 61, 50, 79, 57
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OFFSET
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1,2
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COMMENTS
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Conjecture: a(388) = 0, i.e., A065091(388) = 2683 doesn't occur in A075323;
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LINKS
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EXAMPLE
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Also a(389) = 0 (presumably), whereas subsequent terms (n > 389) are > 0:
393,443,421,350,397,455,368,433,387,352,356,382,384,366,372,392,374, ...
with corresponding odd primes:
2689,2693,2699,2707,2711,2713,2719,2729,2731,2741,2749,2753,2767,2777, ...
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MATHEMATICA
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maxm = 3000;
A075321p[n_] := A075321p[n] = Module[{prevlist, i, p, q}, If[n == 1, Return[{3, 5}], prevlist = Array[A075321p, n-1] // Flatten]; For[i = 2, True, i++, p = Prime[i]; If[FreeQ[prevlist, p], q = p + 2*n; If[ PrimeQ[q] && FreeQ[prevlist, q], Return[{p, q}]]]]];
A075323[n_] := If[OddQ[n], A075321p[(n + 1)/2][[1]], A075321p[n/2][[2]]];
a[n_] := For[m = 1, m <= maxm, m++, If[A075323[m] == Prime[n + 1], Return[m]]] /. Null -> 0;
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PROG
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(Haskell)
import Data.List (elemIndex); import Data.Maybe (fromJust)
a247233 = (+ 1) . fromJust . (`elemIndex` a075323_list) . a065091
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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