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 A105407 Indices n of primes p(n), p(n+4) such that p(n)-1 and p(n+4)-1 have the same largest prime factor. 0
 3, 4, 8, 10, 21, 25, 54, 67, 122, 304, 436, 640, 647, 1106, 1917, 2292, 3622, 3783, 10285, 10600, 14785, 20211, 21804, 137507, 383436, 413254, 662294, 766759, 841376, 880622, 1406141, 1882958, 2051870, 2896609, 3033094, 3201710, 4937565, 6544495, 19611983, 33204098, 40184934, 473909315, 475815668, 662860224, 889407349 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..45. PROG (PARI) \prime indices such that gd of prime(x)+ k and prime(x+m) + k are equal divpm1(n, m, k) = { local(x, l1, l2, v1, v2); for(x=2, n, v1 = ifactor(prime(x)+ k); v2 = ifactor(prime(x+m)+k); l1 = length(v1); l2 = length(v2); if(v1[l1] == v2[l2], print1(x", ") ) ) } ifactor(n) = \Vector of the prime factors of n { local(f, j, k, flist); flist=[]; f=Vec(factor(n)); for(j=1, length(f[1]), for(k = 1, f[2][j], flist = concat(flist, f[1][j]) ); ); return(flist) } CROSSREFS Sequence in context: A233771 A072606 A098764 * A222395 A222269 A310011 Adjacent sequences: A105404 A105405 A105406 * A105408 A105409 A105410 KEYWORD nonn AUTHOR Cino Hilliard, May 01 2005 EXTENSIONS 8 more terms from R. J. Mathar, Feb 14 2008 a(32)-a(45) from Donovan Johnson, Apr 03 2008 STATUS approved

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Last modified April 21 23:44 EDT 2024. Contains 371886 sequences. (Running on oeis4.)