login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A109181
a(n) = A003132(A052034(n)).
4
2, 13, 17, 37, 73, 2, 11, 11, 59, 59, 131, 83, 131, 163, 17, 89, 11, 19, 59, 19, 67, 43, 67, 139, 139, 17, 97, 41, 113, 53, 61, 101, 37, 53, 61, 101, 73, 109, 131, 67, 139, 107, 179, 149, 109, 137, 83, 163, 139, 131, 179, 163, 211, 11, 83, 11, 19, 83, 131, 11, 83, 47, 67, 103, 11, 19, 59, 47, 107, 43, 67, 107, 179, 47, 127, 167, 199, 131, 67, 163
OFFSET
1,1
COMMENTS
For the primes p see A052034.
FORMULA
a(n) = A003132(A052034(n)). - Zak Seidov, Dec 30 2013
EXAMPLE
q=13 is a term because 13 = 2^2 + 3^2 and merging digits 2 and 3 makes p=23, which is a prime.
MAPLE
a:=proc(n) local nn, L: nn:=convert(n, base, 10): L:=nops(nn): if isprime(n) = true and isprime(add(nn[j]^2, j=1..L))=true then add(nn[j]^2, j=1..L) else end if end proc: seq(a(n), n=1..1200); # Emeric Deutsch, Jan 08 2008
CROSSREFS
Sequence in context: A177964 A174050 A122487 * A175448 A067522 A128852
KEYWORD
base,nonn
AUTHOR
Zak Seidov, Jun 21 2005
EXTENSIONS
More terms from Emeric Deutsch and Alvin Hoover Belt, Jan 08 2008
STATUS
approved