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A155740 Odd numbers that are the concatenation of a prime p and the p-th nonprime nonnegative integer. 1
21, 1725, 1927, 2333, 3751, 79105, 83111, 131169, 167213, 173219, 191243, 193245, 197249, 227287, 229289, 251315, 269335, 307381, 317393, 367453, 379469, 383473, 397489, 419515, 421517, 431529, 433531, 439537, 449549, 463565, 499609, 521635 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
21 is a term because it is the concatenation of 2 (a prime) and the 2nd nonnegative nonprime integer 1 (which is odd);
1725 is a term because it is the concatenation of 17 (a prime) and the 17th nonnegative nonprime integer 25 (which is odd).
MAPLE
cat2 := proc(a, b) dgsb := max(1, ilog10(b)+1) ; a*10^dgsb+b ; end proc:
A155740 := proc(n) p := ithprime(n) ; c := A141468(p) ; if type(c, 'odd') then cat2(p, c) ; printf("%d, ", %) ; end if; return ; end proc:
seq(A155740(n), n=1..120) ; # R. J. Mathar, May 15 2010
CROSSREFS
Sequence in context: A130039 A221033 A221497 * A278776 A296597 A203327
KEYWORD
nonn,base,less
AUTHOR
EXTENSIONS
Corrected (1321 removed, all terms >= 200000 corrected) by R. J. Mathar, May 15 2010
Name and Example section edited by Jon E. Schoenfield, Feb 14 2019
STATUS
approved

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Last modified June 22 22:30 EDT 2024. Contains 373622 sequences. (Running on oeis4.)