OFFSET
4,1
COMMENTS
Let S(n) = Sum_{k=4..n} a(k). Is the sequence of integers b(m) such that S(b(m)) > 4*b(m) finite? The first 3 terms are b(1)=794, b(2)=795, and b(3)= 1326. Is -4 <= 4*n-S(n) <= 13 always true? Is a(n) bounded?
LINKS
Robert Israel, Table of n, a(n) for n = 4..10000
FORMULA
Probably lim_{n -> infinity} S(n)/n = lim_{n -> infinity} (1/n)*Sum_{k=4..n} a(k) = 4.
PROG
(PARI) a(n)=if(n<0, 0, k=1; while(abs(prime(k+n)%10-prime(n)%10)>0, k++); k)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Benoit Cloitre, Aug 13 2002
EXTENSIONS
Edited by Jon E. Schoenfield, Jan 18 2020
STATUS
approved