A152606 - OEIS

%I #11 Feb 04 2018 03:22:05

%S 1,2,3,4,5,8,9,21,45,83,89,450,503,630,701,810,901,2101,2103,4121,

%T 6301,6303,6503,6901,43030,70103,81010,90101,210101,210103,210107,

%U 210109,210143,210145,210149,210161,210163,210167,210169,210503

%N a(1) = 1; thereafter a(n) is always the smallest integer > a(n-1) not leading to a contradiction, such that any six consecutive digits in the sequence sum up to a prime.

%C Computed by Jean-Marc Falcoz.

%C From a(269) = 1010001010 on, there starts a pattern of 104 terms, which then repeats indefinitely (with 6 digits in the middle of each term duplicated). - _M. F. Hasler_, Oct 16 2009

%H Eric Angelini, <a href="http://www.cetteadressecomportecinquantesignes.com/ConsecDig.htm">Chiffres consecutifs dans quelques suites</a>

%H E. Angelini, <a href="/A152136/a152136.pdf">Chiffres consecutifs dans quelques suites</a> [Cached copy, with permission]

%o (PARI) a(n, show_all=0, s=[1, 2, 3, 4, 5, 8, 9, 21, 45, 83, 89, 450, 503, 630, 701, 810, 901, 2101, 2103, 4121, 6301, 6303, 6503, 6901, 43030])={ my(a,nd=#Str(s[ #s])); for(i=1,n, if( i<=#s, a=s[i], my(ld=a%10^nd); while(a++,my(t=a+ld*10^#Str(a));forstep(d=#Str(a)-1,0,-1,isprime(sum(j=d,d+nd,t\10^j%10))&next;a+=10^d-a%10^d-1; next(2));break));show_all & print1(a", "));a} \\ _M. F. Hasler_, Oct 16 2009

%Y Cf. A158652, A152604, A152605, A152607, A152608, A152609.

%K nonn,base

%O 1,2

%A _N. J. A. Sloane_, Sep 23 2009