The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A282633 Numbers n such that n^2 + 1 is the sum of two proper prime powers (A246547) in more than one way. 1
 47, 73, 83, 133, 157, 173, 187, 191, 203, 217, 317, 319, 353, 437, 463, 467, 487, 499, 557, 577, 583, 593, 599, 613, 623, 697, 703, 727, 733, 767, 829, 857, 863, 871, 931, 983, 1013, 1027, 1033, 1067, 1087, 1097, 1123, 1139, 1177, 1267, 1279, 1321, 1327, 1333, 1363, 1403, 1409, 1433, 1453, 1477, 1487, 1493, 1507, 1517, 1543, 1567, 1603, 1607, 1613 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Robert Israel, Table of n, a(n) for n = 1..2672 EXAMPLE 83 is a term because 83^2 + 1 = 7^4 + 67^2 = 43^2 + 71^2. MAPLE N:= 10^8: # to get all terms <= sqrt(N-1). PP:= sort([seq(seq(p^k, k=2..floor(log[p](N))), p = select(isprime, [2, seq(i, i=3..floor(sqrt(N)), 2)]))]): npp:= nops(PP): res:= {}: R:= 'R': for i from 2 to npp do    for j from 1 to i-1 do      q:= PP[i]+PP[j];      if q > N then break fi;       if issqr(q-1) then        if assigned(R[q]) then res:= res union {q}         else R[q]:= 1       fi fi od od: sort(convert(map(t -> sqrt(t-1), res), list)); CROSSREFS Cf. A002522, A225103, A246547. Sequence in context: A094335 A300165 A316351 * A052231 A092178 A165335 Adjacent sequences:  A282630 A282631 A282632 * A282634 A282635 A282636 KEYWORD nonn AUTHOR Robert Israel and Altug Alkan, Feb 19 2017 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 29 03:06 EDT 2020. Contains 334696 sequences. (Running on oeis4.)