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A046804
a(n) = p mod (p mod 10) where p = prime(n).
1
0, 0, 0, 0, 0, 1, 3, 1, 2, 2, 0, 2, 0, 1, 5, 2, 5, 0, 4, 0, 1, 7, 2, 8, 6, 0, 1, 2, 1, 2, 1, 0, 4, 4, 5, 0, 3, 1, 6, 2, 8, 0, 0, 1, 1, 1, 0, 1, 3, 4, 2, 5, 0, 0, 5, 2, 8, 0, 4, 0, 1, 2, 6, 0, 1, 2, 0, 1, 4, 7, 2, 8, 3, 1, 1, 2, 2, 5, 0, 4, 5, 0, 0, 1, 7, 2, 8, 2, 0, 1, 5, 2, 4, 0, 4, 2, 5, 0, 1, 0, 1, 4, 2, 2, 0
OFFSET
1,7
COMMENTS
From Robert G. Wilson v, Feb 12 2014: (Start)
a(n)=0 iff p ends in 1 (A030430) or is a single-digit prime, i.e., 2, 3, 5 or 7 (n = 1, 2, 3 or 4),
a(n)=3 iff n is in A142087,
a(n)=6 iff n is in A142094,
a(n)=7 iff n is in A142330,
a(n)=8 iff n is in A142335.
a(n) can never be 9. (End)
REFERENCES
Idea derived from "The Creation of New Mathematics: An Application of the Lakatos Heuristic," pp. 292-298 of Philip J. Davis and Reuben Hersh, The Mathematical Experience, Houghton Mifflin Co, 1982. ISBN 0-395-32131-X.
EXAMPLE
prime(10) = 29, so a(10) = 29 mod 9 = 2.
MATHEMATICA
Mod[#, Last[IntegerDigits[#]]]&/@Prime[Range[110]] (* Harvey P. Dale, Jan 23 2013 *)
Mod[#, Mod[#, 10]]&/@Prime[Range[110]] (* Harvey P. Dale, Aug 22 2020 *)
CROSSREFS
Sequence in context: A324123 A016570 A070773 * A263211 A287571 A214316
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
Name edited by Jon E. Schoenfield, Jan 19 2023
STATUS
approved