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 A320879 Primes such that iteration of A062028 (n + its digit sum) yields 7 primes in a row. 5
 286330897, 10858338851, 12869802851, 15845166851, 29837412851, 45480846799, 56676324799, 56676324863, 68105187851, 73915118861, 114737845853, 129282912851, 154648223809, 155738371853, 207036953861, 271077075851, 358515148853, 373169411809, 373169411861, 395705343799 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The first 15 terms are immediately calculated from A320878(1..200) using the formula. LINKS Lars Blomberg, Table of n, a(n) for n = 1..445 (Terms < 10^14) Carlos Rivera, Puzzle 163. P+SOD(P) FORMULA A320879 = { n in A320878 | A062028(n) in A320878 } = { n = A320878(k) | A062028(n) = A320878(k+1) }. PROG (PARI) is_A320879(n)=isprime(n=A062028(n))&& is_A320878(n) \\ If possible, use this to select terms from a sufficiently large precomputed array A320878: A320879 = select( is_A320879, A320878) \\ or, in that case, the more efficient: A320879 = select( p->setsearch(A320878, A062028(p)), A320878) \\ or: vecextract(A320878, select(i->A062028(A320878[i])==A320878[i+1], [1..#A320878-1])) CROSSREFS Cf. A047791, A048519, A062028 (n + digit sum of n). Cf. A048523 .. A048527. a(1) = A090009(8) = start of first chain of 8 primes under iteration of A062028. Subsequence of A320878; A320880 is a subsequence. Sequence in context: A267824 A185428 A320878 * A214155 A183737 A234807 Adjacent sequences:  A320876 A320877 A320878 * A320880 A320881 A320882 KEYWORD nonn,base AUTHOR Zak Seidov and M. F. Hasler, Nov 08 2018 EXTENSIONS a(16)-a(20) from Lars Blomberg, Feb 10 2019 STATUS approved

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Last modified August 15 13:27 EDT 2020. Contains 336504 sequences. (Running on oeis4.)