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 A090009 Begins the earliest length-n chain of primes such that any term in the chain equals the previous term increased by the sum of its digits. 3
 2, 11, 11, 277, 37783, 516493, 286330897, 286330897, 56676324799 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Carlos Rivera, Puzzle 163. P+SOD(P) EXAMPLE 11 begins the earliest chain 11, 13, 17 of three primes such that any term in the chain equals the previous term increased by the sum of its digits, viz., 13 = 11 + 2, 17 = 13 + 4. Hence a(3) = 11. MAPLE with(numtheory); A090009:=proc(q) local a, b, c, d, j, n; d:=0; for n from 1 to q do   a:=0; c:=ithprime(n); j:=c;   while isprime(c) do    a:=a+1; b:=0; while c>0 do b:=b+(c mod 10); c:=trunc(c/10); od;    c:=j+b; j:=c; od;    if a=d+1 then d:=a; lprint(d, ithprime(n)); j:=1;    else if a>d+1 then for j from 1 to a-d do lprint(d+j, ithprime(n)); od; d:=a; fi; fi; od; end: A090009(10000000000); # Paolo P. Lava, Jun 07 2012 CROSSREFS Sequence in context: A153705 A245521 A275617 * A153706 A201187 A068225 Adjacent sequences:  A090006 A090007 A090008 * A090010 A090011 A090012 KEYWORD base,more,nonn AUTHOR Joseph L. Pe, Jan 27 2004 EXTENSIONS a(7)-a(8) from Donovan Johnson, Jan 08 2013 a(9) from Giovanni Resta, Jan 14 2013 STATUS approved

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Last modified July 20 12:11 EDT 2017. Contains 289626 sequences.